Converts your WE M4 closed system to open chamber system.
Open bolt M4 mags are required to be used with this kit.
One set of mag conversion kit is included
M4/SCAR Open Bolt Mag Conversion Kits
M4/SCAR Open Bolt Magazines
NOTE: this version has the "tabbed" hop-up unit, which secures snugly into the upper receiver, and is beneficial for proper mag seating.