Archwick CNC Stainless Steel BB Detents for Archwick Pinnacle Hop Up Units for MK13 and VSR-10.  These CNC Stainless Steel BB Detents are a direct drop in upgrade over the standard polymer BB Detants as used on your Pinnacle Hop Up units.  
As used in B & T Air SPR 300 Bolt Action Rifle
CNC Machined Stainless Steel
Fits Pinnacple Hop Up units for Archwick MK13 and Tokyo Marui VSR 10 Sniper Rifles
Fits Action Army CNC Hop Up units