This barrel extension set from Echo1 includes 3 different length extensions which are threaded -14mm. The Echo1 extension allows for use of a slightly longer inner barrel, or mounting a silencer or other accessory.
If you're looking to mount a Surefire mock suppressor but don't have the necessary barrel overlap, the Echo1 barrel extension set is the ideal solution. With 3 lengths, any custom job is possible on almost any AEG.
Long: 110mm (including threads)
Mid: 55mm (including threads)
Short: 35mm (including threads)