I liked up a double-mag carrier with a AR mag carrier so it's one secure piece on my belt line. Does exactly what it says - gives you two different size screws, plus the washer and nut so you can link RCS gear together.
Modular Product Linking Hardware
Linking Hardware Kit:
Qty 4 - o-rings
Qty 2 - slotted steel post
Qty 2 - 1/2" screw
Qty 2 - 3/4" screw
Qty 1 - thread locker
This hardware pack is used to attach any of our modular holsters, mag carriers, or other modular products to one another. For example, you can attach a single mag carrier to a double to create a tripple mag carrier. Or attach and M4 mag carrier to a single pistol mag carrier. The possibilites to customize your carry equipment to meet your needs are up to your imagination.