Check the size of carrier first – look inside the carrier between the clip screws to see what size carrier you were shipped.
S means Single Stack
D means Double Stack
9 means 9/40 magazines
45 means 45 magazines
The magazine will be loose in the Echo Carrier at first. You will need to tighten the (MRD) mag retention device with the included 1/8 allen wrench for best fitment. We recommend removing the magazine before adjusting the retention device. Adjust in quarter-turn or fewer increments. If your magazine is loose or rattles in the carrier, keep adjusting the retention device for the desired fitment.