ZCI Double O-Ring Aluminium Bearing Piston Head

£8.95

CNC machined from solid aluminium for strength and precision
Double O-ring design for maximum air seal and compression
Ventilated crown pushes the O-ring out for a tighter seal
Integrated ball bearing cuts friction on spring cycling
Standard fitment for Version 2 and Version 3 AEG gearboxes
Tested to pair cleanly with ZCI or SHS cylinder sets

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Description
Specification

ZCI double O-ring bearing piston head

Compression is everything in an AEG gearbox, and this ZCI piston head is a proven, affordable way to sharpen it. It is CNC machined from solid aluminium with a double O-ring, a ventilated crown and an integrated ball bearing, delivering a strong air seal and smooth spring cycling.

How the double O-ring and vents work

The double O-ring configuration maximises the seal against the cylinder wall for stronger compression. The vented crown lets air push the O-ring outward as the piston compresses, forming an even tighter seal at the moment it matters most for a more consistent shot.

Fitment and compatibility

It is a standard fitment for Version 2 and Version 3 AEG gearboxes, covering the majority of M4, AK and MP5 style electric guns, and pairs cleanly with ZCI or SHS cylinders and cylinder heads. Always check against your existing head before building. Browse more airsoft accessories.

Fitting advice

Add a dab of thread lock to the piston head screw so it cannot work loose under the repeated shock of firing. Our Kent repair workshop can handle the build if you prefer.

Product information reviewed by James Smith. Every gun is checked & serviced by our Rochester workshop before dispatch.

General
Brand	ZCI
Other
Type	AEG piston head
Material	CNC aluminium
Bearing	Integrated ball bearing
Sealing	Double O-ring
Design	Ventilated crown
Gearbox compatibility	Version 2 / Version 3 AEG
Part reference	M-279C
Fitment	Drop-in replacement for plastic head
Pairs with	Standard AEG cylinders and cylinder heads
Legal status	Internal part, no FPS restriction
Finish	Anodised (colour may vary)

Recommended upgrades & accessories

Frequently asked questions

Which gearboxes does it fit?

It is a standard fitment for Version 2 and Version 3 AEG gearboxes, which covers the majority of M4, AK and MP5 style electric guns. Always check against your existing head before building.

What does the vented design do?

The ventilation holes let air push the O-ring outward against the cylinder wall as the piston compresses, forming a tighter seal at the moment it matters most for a stronger, more consistent shot.

Why does it have a ball bearing?

The bearing lets the head rotate freely as the spring loads and unloads, reducing friction and wear inside the gearbox and giving smoother, more repeatable cycling.

Should I use thread lock?

Yes, a dab of thread lock on the piston head screw is good practice so it cannot work loose under the repeated shock of firing.

Do I need a UKARA or to be 18?

No. This is an internal spare part, not a firearm, so there is no UKARA requirement and no age restriction on purchase.

ZCI Double O-Ring Aluminium Bearing Piston Head