Box One™ Chain Tensioners are extruded then CNC-machined from 7075 aluminum for an optimal balance of strength and weight

and manufactured using the same engineering found on their legendary Thunderbolt cranks

The unique cable pivot design and straddle cable system create a smoother and more powerful pull

their quest to develop some of the toughest cranks on the market paid off after machine testing and riding testing proved them to be insanely strong

Box One BMX Race Disc Brake Adapter (Sliding Dropout) - Black supplier_55074282209606 Box One™ Chain Tensioners areThe Box Disc Brake Adapter is designed to help improve braking control on frames where disc brakes were not standard. Compatible with 2 types of dropouts and 3 10mm hubs, in the right configurations, the Box Disc Brake Adapter goes over your hubs axle and mates with the frames dropout, allowing mounting of a standard post mount disc brake caliper.