The Radical Rail System offers a larger inside diameter designed to accommodate your suppressor or for those that like the feel of a full sized quad rail. At 1.8” inside diameter your suppressor easily fits inside and the cutouts on the rail aid in rapid cooling. The Radical Rail System features anti-rotation tabs, built in non-rotating QD sling mounts, Key-mod rails that allow you to run without rail covers, allows any accessories and is hard anodize coated and super awesome if we say so ourselves. The Radical Rail lengths 9”(13.1oz), 12”(18.6oz). Manufacturer has discontinued the 15” model.