From the manufacturer:
While not officially rated/tested for a given weight these micro D-shape caribiners are tough and they’ll handle more abuse than you might expect. The spring steel wire gate makes latching easy, firm, and reliable.
A wire-gate carabiner has a length of bent steel wire that serves as the gate. Unlike a bar-stock carabiner gate, which has multiple moving parts, including a small internal spring, a wire-gate is but one piece. The wire itself functions as both gate and spring. Its simplicity yields many benefits: These units are less apt to gunk-up, are inherently easier to clip, open wider, and weigh less than bar gates.