Madbull Ultimate 3-in-1 Hop-Up Chamber Unit M4/M16 by Madbull

The product is real sturdy. It fit right into my m16 it’s not fully snug but it fit great. And I love how the bb don’t drop out when taking out the mag. I gotta test range and accuracy tho

Haven't try it suck that it don't fit my classic army m4

Worked greasy on my ICS CXP-08 and feed bbs with out any issues

Perfect fix to my hop up issue! I have a polarstar jack and had trouble finding a hop up unit that worked nicely. This was my answer works amazingly.

Gotta say better than anticipated, No more hanging up and it’s smooth and easy to assemble. If your looking for a an affordable hop up unit, this is it.