Rackstuds Smart Rack Mounting System, 100-pack A universal replacement for cage nuts* Inserts from the front so no more fiddling behind the rack Rackstuds&#0153; provide a place to support your gear Rackstuds&#0153; are much simpler, faster, safer and very strong Suitable for rails up to 2.2mm/0.086" only. Use the new 'blue' version if your rail &gt;2.2mm/0.086"