The PDI VSR-10 Hopup Chamber, newer 2.0 version. Probably the best hop-up chamber for the VSR gun in existence! A very cool accessory for those wanting the most from their airsoft sniper rifle. This is an advanced adjustable hopup unit - not for amateur players. Made in Japan by PDI. Will not work with all original VSR parts, a full list of requirements is listed below. You have to use an AEG style barrel and AEG hop up bucking in this chamber. Killer hopup by PDI!