Utg rail picatinny ar-15 9" 2-pc drop-in mid-length FEATURES-8.68"L x 2.44"W x 2.44"H-Clever top/bottom 2-piece design with integral spinal cords/alignment housing for great fit-Designed with innovative alignment tabs at the front for perfect fit with the standard triangular front cap-Fits middle length Model 4/15-Includes 4 Picatinny rails each with 18 continuous slots-Great zero-retention capability for all accessories installed on the rails-Easy installation with no modification to the barrel-Black rubber rail guards included-Proudly made in the USA Other Features: Two piece drop-in, made in usa