Fortis Manufacturing, Inc., Light Weight K2, Castle Nut and End Plate, Black and Gray, Anodized Finish WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov Lightweight design at only .55 oz / 16.8 grams total Castle nut and end plate are 7075 T6 Aircraft Grade Aluminum Quick Detach Socket - 360 rotational locking interface No set screws or ratcheting system Made in the USA When designing their new Lightweight Enhanced (LE) Castle Nut & End Plate System, Fortis came up with two systems that virtually eliminates the risk of your castle nut ever backing out. With two lockdown systems (K1 & K2), Fortis has engineered a solution to install the castle nut onto the end plate that is not only robust, but also stands true to their brand of innovation and ingenuity. The K1 system features a tapered castle nut that seals itself onto the end plate. This ultra precision snug fit allows the castle nut to seat and seal itself into place without the need of staking the end plate. No ratcheting, no set screws, no backing out and no failures. All of these features at only .59 oz / 16.8 grams! Specifications