The Whisper is the highest performance polymer piston head on the market and our new go-to piston head for virtually all builds: 
 
Delrin CNC machined
Very low coefficient of friction and extremely high impact resistance
Elongated shaft to allow more AoE spacers
Grade 12.9 zinc plated screw
Superior corrosion resistance and strong enough to strip cheap allen keys before the screw gives out. 2mm hex drive
CNC 7075 T6 Aluminium Threads
Dual Port Design
Dual porting to reduce vacuum effect and for more usable air volume in high rate of fire applications
European Manufactured NBR O-ring 
Great  abrasion resistance and low temperature performance coupled with high tensile/compression strength.
Bronze (6g) and Delrin (1g) Bushing Included
USE ONE OR THE OTHER ONLY - Lightweight Delrin for when you want to go fast or heavy Bronze for when you want to sling heavy weight bbs. (Total Weight: 7-11g)
 
Please note: Loctite 266 or equivalent is required when fitting