Spikes Tactical SLA501S: The Spike\'s Tactical Buffer Spring is the same high quality carbine buffer spring that\'s found in their complete rifles, complete lowers, and in their various stock kits. It\'s a Mil-Spec 17-7 stainless steel buffer spring that features an electro polish finish to give it a smoother quality look and feel. If you need a replacement buffer spring or just need one to finish a build, look no further. Get one today. Note: Only for use in a carbine buffer tube, or in a rifle length buffer tube with the Spike\'s Tactical ST-T0 spacer.