Rack rails can be installed into racks with square, round or threaded holes. Rack mount equipment weighing up to 200 lbs (91 kgs) can be installed using rack rails. The rack rail can be installed into server racks with installation depths from 10" - 24" (254 - 609.6 mm). Adjustable Rack Rails and Square Hole Mounting The rail kit depth is fully adjustable from 10"-31.75" (254mm-806mm) all by loosening the screws and nuts. The rail kit is made from 18 GA steel and is zinc plated. The RackSolutions Universal rail kits are square hole to allow for the rails to be compatible with round, square or threaded hole racks. The rails to be compatible with round, square or threaded hole racks.