Fps Ergal/POM cylinder set for M4 standard electric gun (hi speed)

New improved set with light weight ergal dual oring piston head with ball bearing
hi drain cylinder head with enlarged oring 
POM nozzle with internal oring included
steel polished hi pressure cylinder 
suitable with 301mm at 400mm
this set will enhance the accuracy and shooting performance

for Marui M4 electric gun series and compatible