Leapers, Inc. - UTG Handguard, Fits AR Rifles, 13 Super Slim, Free Float M-LOK, Black MTU006SSM The UTG pro M-LOK AR-15 13" super slim free float handguard has a proprietary barrel nut design. It features 42 M-LOK slots on 7 slot tracks for mounting M-LOK rails and direct accessories. It has a 31 slot picatinny top rail" flush fitting and continuous with flat top AR-15 upper receivers" providing ample space for optics and other accessories. It includes an 8-slot picatinny rail section and a QD sling swivel adaptor for sling swivel attachment.