Cross Industries - 5.56 NATO 10/10 Cross Mag Coupling AR-Pistol 10-Round Magazine Set - Smoke Black :
Featuring a unique coupling mechanism integral to the floor plate, couple two magazines end-to-end in 4 unique configurations in seconds, allowing faster reloads so you can RETURN MORE FIRE

Designed and manufactured in a state of the art factory in Canada, Cross industries knows what it takes to withstand frigid temperatures, rough handling and competition use. The transparent bodies allow quick visual indication of how many rounds you have left, or the type of rounds, which is particularly useful for running a mixed mag. The integral coupling floor plate allows you to couple the magazines end-to-end in either a curved or straight configuration, from there you decide if you want your cartridges facing forward forward, or forward reverse. If you ever change your mind about a configuration, change it seconds, without extra parts or special tools. Or heck, un-couple the mags and take advantage of low-profile mags to shoot prone, on a bench or hunt in the woods.

Designed to perform in the frigid north, this polymer is a new to market material that is specially formulated for cold weather impact resistance. Its unique properties allow virtually no change in mechanical properties from 20c to -30c, whereas most polymer materials used for magazines have between .125-.25 the strength at -30c compared to room temperature. This gives Cross on average 3-8x better impact resistance than competitive materials in the cold.