The only CF barrel to use Smart Parts Freak inserts. The Deadlywind Fibur carbon fiber barrels are ultra-lightweight, accurate, and quiet. They utilize the Freak(tm) replaceable inserts, so one barrel and a few inserts will do the job of multiple barrels. Note- You MUST use a Smart Parts "Freak" insert with this barrel - available on our store. Weighing in at an average 60grams (73 grams with insert), the Fibur is 2x to 4x lighter than other replaceable insert barrels. And it it is strong enough to be driven over with a car (Yes, we have done it-- And we do not suggest you try it on purpose!) Unlike other carbon fiber barrels, the Fibur barrel is built with a unique 3 layer construction. 2x2 satin Twill external, uni-direction fibers laid up in a strong multi-vector pattern, and then a super slick "Silkfiber" inside that can be safely swabbed. CNC align-bored segment for the insert area, CNC-ported with 3 rows of straight ports, and then hand-assembled and quality checked-- You can't get any more accurate.