model #6/1 this dove to weaver super low adapter has a spring loaded mechanism to fit "under" any weaver / picatinny scope rings or accessory mount (eg dot sight), then fit to the dovetail rail and tighten screws on the rings/accessory mount which will secure the whole lot to the dovetail rail. (this is one rail, not a pair but you can order as many single ones as you want). Black alloy grub stop pin dovetail base adjusts from 11-14mm 20-22mm weaver top 25mm long 4mm profile height + 4 slot and 9 slot option listed separately.