Hydra Pen H6 vs H3 vs H5 vs H2: Where the Serum Sits, and What That Changes

Four pens sit in the Hydra line, and what separates them is not a ranking. It is where the serum sits while the head is working. On one pen the serum travels inside the head itself; on the other three it travels inside the pen and is fed out through the head. That arrangement decides what gets refilled, what gets replaced, how deep the pen reaches, and how much of the routine is still done by hand.

This article compares the Hydra Pen H6 with the H3, the H5 and the H2 on that single axis. Pens outside the line sit on a different question, whether the pen carries product at all, and those comparisons belong with a standard Dr. Pen and with the Bio Pen Q2 rather than here.

The short answer

If the step you want removed is re-applying product section by section, all four pens address it, and the choice between them is about how the top-ups happen rather than whether they happen. The Hydra Pen H6 carries the serum in the head; the H2, the H3 and the H5 carry it on the pen.

If you want the widest depth range in the line, that is the H6, and it is the only one of the four that reaches past 1.0 mm. If you want the simplest arrangement, the H2 is the one with no flow control to set: the container is built into the pen and the depth comes from the head you fit.

One thing does not change across all four. On the face, a home routine stays at or below 1.0 mm, whatever the pen is capable of reaching.

Two ways the serum reaches the skin

The table below is the whole article in one frame; everything after it is a detail of one of the two columns.

	Carried in the head	Carried in the pen
Pens	Hydra Pen H6	Hydra Pen H2, H3 and H5
What the head carries	A 3 mL reservoir together with the needles	The needles only; the pen feeds the product out through them
Where the container sits	In the head, and it leaves with the head	On the pen: built in on the H2, adjustable on the H3, detachable on the H5
Depth the pen reaches	0.25 to 2.0 mm	0 to 1.0 mm on the H3 and H5; 0.25, 0.5 or 1.0 mm on the H2
How depth is set	A control on the pen	A dial on the H3 and H5; on the H2, the head you fit
Built in beyond needling	630 nm red and 470 nm blue light	EMS microcurrent on the H5

A pen that carries no product at all is a third arrangement rather than a place on this table, and it changes what the routine is built around rather than how much serum a pen holds.

What the architecture changes in a routine

• Where the top-ups happen — with a container, product is laid down as the head travels, so a section is not interrupted to reapply by hand; the container is refilled when it runs low rather than at every change of area.
• What you buy again — the head is the consumable in every case, because the needles are intended for a single session. On the H6 the head is also the product path, so a spent head ends the session's supply as well as its needles.
• What the needles still do — needling is what opens the micro-channels on all four pens. A container changes neither how deep the needles reach nor which head suits which area.
• Where the two arrangements diverge most — at the end of a session. A pen-carried container is emptied or topped up while the pen stays in use; an H6 head is finished when the head is finished.

Depth, Hydra pen by pen

• Hydra Pen H2 — 0.25, 0.5 or 1.0 mm, decided when the head is bought — the pen carries no depth dial, so depth is fixed at the cart rather than adjusted mid-session.
• Hydra Pen H3 and H5 — 0 to 1.0 mm on the pen — both adjust depth on the device itself, and both take the same heads, so the range on the two is identical.
• Hydra Pen H6 — 0.25 to 2.0 mm, held electronically — the widest range in the line, set from the pen's own control and shown on the display while you work.

The safe depth for each area is the same on all four, because it is set by skin anatomy rather than by the device.

Where the product is held, pen by pen

The three pen-carried Hydra Pens do not hold serum in the same way. The H2 delivers through the head from a container built into the pen, with no separate flow control. The H3 has an adjustable infusion amount, so delivery can be matched to the area. The H5 uses a detachable container that can be filled away from the pen, with flow set across three levels for products of different thickness. On all three the container stays with the pen when the head is replaced. On the H6 that is inverted: the container is part of the head, so it is filled per head and leaves with it.

Genuine heads for each of these pens are listed separately: H6 heads, H2 heads and H3 and H5 heads. Choosing by pin count rather than by family is covered in this explanation of the pin counts.

Head families, and what crosses over

This is the question that arrives most often after a purchase, and within this line the answer is short: no family crosses into another.

Head family	Pens it fits	Heads in it
Hydra Pen H6 family	H6 only	18, 36 and 42-pin, plus Nano-R
Hydra Pen H3 and H5 family	H3 and H5	12, 24 and 36-pin, plus round and square nano
Hydra Pen H2 family	H2 only	12-pin at a fixed 0.25, 0.5 or 1.0 mm, plus Nano-HS and Nano-HR

A head that seats with a light click belongs to the pen in your hand; one that resists belongs to another family. Force should never be used to seat a head. The full head range lists every family separately.

What the H6 does that no other Hydra Pen does

• The product path travels with the head — on the H2, H3 and H5 the container stays on the pen and the head is replaced alone; on the H6 the part that meets the skin and the part that holds the product are one unit.
• It reaches twice as deep as the other three — 0.25 to 2.0 mm against the 1.0 mm ceiling of the H3 and H5, with the top of that range left to trained practitioners.

What this article does not compare

It does not rank these pens by how well they work: no page in this range publishes a comparative figure, and a comparison article is the wrong place to invent one. It does not compare price, which each product page carries. It does not cover the RF handpieces or the stamp and roller formats. And it does not set a treatment interval, which depends on the depth used rather than on which pen is on the table.

Frequently asked questions

Where does the serum sit on an H6 compared with an H2, an H3 or an H5?

On the H6 the chamber is inside the head, so it is filled when the head is fitted and it leaves with the head. On the H2, H3 and H5 the chamber belongs to the pen and only the needles are thrown away.

If the H3 and the H5 both set depth on the pen, what separates the two?

How the product is held. The H3 keeps its chamber fixed to the pen and lets you set an infusion amount; the H5 lets the chamber come off so it can be filled away from the pen, and offers three flow levels for products of different thickness. Their head families are one and the same.

The H6 keeps its reservoir in the head, so what happens to serum left in it when the head is changed?

It goes out with the head. That is the trade the H6 makes: the chamber is never carried between sessions, and a part-filled head cannot be set aside and continued later.

Does the choice between these four come down to depth range, or to how the serum gets delivered?

Both, in that order of visibility. The depth ceiling separates the H6 from the other three; the delivery arrangement separates the H2 from the H3 and H5. Working backwards from the step you dislike is usually faster than working forwards from the specifications.

What depth does a home facial routine need on any of these four pens?

The same as on any other device: at or below 1.0 mm on the face. Three of these four pens cannot exceed that anyway, and the H6 can, which makes the setting rather than the ceiling the thing to watch.

Can the same serum be used in all four Hydra Pens?

There is no serum that one of them will accept and another will refuse. What changes is the chamber, not the liquid: a thicker product needs more flow, and only the H5 and the H6 give you a flow setting to raise.

If the container stays on the pen, does the head still have to be replaced after one session?

Yes. The chamber and the needles are separate parts on the H2, H3 and H5, but the needles are still intended for a single session, so the head is the part that is renewed on all four pens.

Which of the four Hydra Pens reaches deepest, and does that matter at home?

The H6, at 2.0 mm. At home it rarely matters, because a facial routine stops near 1.0 mm whatever the pen offers; the wider range is what makes body work and deeper treatment areas possible at all.

Where to check the current specification and the heads

The four pens with their full contents are listed here: Hydra Pen H6, Hydra Pen H3, Hydra Pen H5 and Hydra Pen H2. Heads are listed by family in the cartridge collection, and every genuine device we ship carries a verification route on our how to verify your Dr. Pen page.

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