These handy little tools are useful for quickly snugging up bolts on accessories that you change and reconfigure often. They can also be installed semi-permanently by running them in reverse (under the bolt head). The Buddies feature a reversable design with heavy knurling for grip. The outer diameter is around 48mm, which allows them to be installed side-by-side on most power racks with 2" (or 50mm) hole spacing. Sold as a pair. Variants: 1" Hardware - 1" nuts and bolts with a 1-1/2" head. This size is commonly used in the Rogue Fitness Monster series. 5/8" Hardware - These fit 5/8" nuts and bolts that take a 15/16" socket. This size is commonly used on the Rogue Monster Lite series and the Titan Fitness T-3 and X-3 racks. M16 Hardware - These fit M16 nuts and bots that take a 24mm socket. This size is often used on REP Fitness 4000 series racks. M18 Hardware - These fit M18 nuts and bolts that take a 27mm socket. We've found this size on some REP Fitness Racks. M20 Hardware - These fit M20 nuts and bolts that take a 30mm socket. These fit some racks made outside of the USA, such as BLK BOX and Cluster Fitness. M24 Hardware - This fits M24 nuts and bolts that take a 36mm socket. Some examples are the REP Fitness PR-4000, PR-1000, and PR-1050 series power racks Please check your hardware size before ordering. If you are unsure, check with the manufacturer to see what hardware they use on your rack.