Designed with extreme gravity riding in mind, the Twinty chain guide fits 2x drivetrains and keeps your chain from falling off even under the most extreme conditions. ISCG 05 mount CNC'd 6061 T-6 Guide Frame Lightweight molded thermoplastic components Made in as few pieces as possible and has no moving parts Captive hardware Highly durable slider made from a proprietary polymer that doesn't wear out like similar guides. No drag! TWINTY 2X guide does not put resistance on the chain like pulley wheel chainguides and makes minimal noise