The Black River Tactical MarkBlue Gas Tube is a premium quality gas tube used exclusively with the BRT EXT length gas system.

The BRT EXT gas system was created to provide OPTIMUM performance from 16" 5.56 barrels.

The BRT EXT gas system is longer than the standard mid-length, but shorter than the Noveske Intermediate length.

Note: Also fits KAC Legacy MOD0/1 and Wilson Combat 13.25"

The distinctive "MarkBlue" dot allows easy identification of a genuine BRT gas tube and guaranteed performance.

It is compatible with BRT MicroPin Gas Blocks, front site bases and low profile gas blocks.