JG Polycarbonate Piston & Piston Head Set w/ Half Steel Teeth

"Great air seal, quality piston. Good and cheap

"I love this piston & head set. Super cost effective. I swiss cheesed it like you wouldn't believe and I'm running and ICS 3-teeth removed short stroked sector gear @ 320FPS .20g BB in my APS UAR resurrected with a custom fab hair trigger. I would consider that a low stress setup so I expect it to last a long time. JG always has reliable parts, but remember to AOE correct your piston AND cylinder head if you want maximum longevity.

"Graet pistol and piston head for five bucks!

"This pistol is awesome! Amazing price and works great! Recommend for all your repair tune up needs

"This piston is stronger than the piston in my stock Classic Army and is much stronger than the Lancer crap. If you have a CA or a Lancer, upgrade the heck out of your gun with this piston.

"This is a good piston/piston head combo for the money. If you can get it on sale for around $7 - $8 then I would say it's worth it. However, be aware that quality control on your piston may vary. I bought two of these and one had perfect meshing between the teeth of the piston and the teeth of the gear while the other piston had an issue where the gear would get stuck at the transition of the plastic teeth and metal teeth of the piston. This issue seemed to be caused by the metal tooth rack sitting too close to the last plastic tooth on the piston. This would cause the gear to get stuck and not cycle smoothly. If you buy this piston make sure that your sector gear rolls smoothly through the rack of the piston, especially at the transition point.

"Great Piston for $5. Most pistons at this price are all plastic teeth and no piston head. Considering this is only $5, half the teeth are steel and it comes with a piston head, THIS IS A GREAT DEAL. Definitely get this if you need a replacement or an upgrade from a plastic tooth piston. Can't say anything else about it since I just installed it in my gearbox.

"awful compression had to stretch the o ring for a whole night and still didnt help

on the other hand, the piston seems well built and is very light

i would recommend for people to buy a separate O ring or piston head

"TLDR: metal and polymer teeth aren't flush. Parted out for piston head and metal teeth.

The insert for the metal teeth doesn't sit even, it starts flush where the piston head is and rises as you go toward the polymer teeth. Beneath the metal tooth insert, the piston itself has a gap and it appears the edges of the gap angle the metal insert upwards, with nothing to push the metal insert back down and keep it flush. I tried it out with my gearbox split and it did not operate smoothly by hand, so I'm not about to trust it under proper power.
Two stars because I was able to salvage the piston head and the metal teeth, but the piston design seems suspect.