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

The BRT EXC gas system was created to provide OPTIMUM performance from 12.5" 5.56 barrels and is excellent for dedicated suppressed 11.5" barrels.

The BRT EXC gas system is longer than the standard CAR length, but shorter than the standard MID length.

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.