AustriAlpin Asymmetric Oval Carabiners are 12mm steel carabiners available in many styles. These biners are CE certified and meet ppe (personal protective equipment) standards. Functional for every day use, they will satisfy you with a long life of service. interlock / Screw Gate Carabiner. Carabiners come in four characteristic shapes: Oval: Symmetric. Most basic and utilitarian. Smooth regular curves are gentle on equipment and allow easy repositioning of loads. Their greatest disadvantage is that a load is shared equally on both the strong solid spine and the weaker gated axis. D: Asymmetric shape transfers the majority of their load onto the spine, the carabiner's strongest axis. Offset-D: Variant of a D with a greater asymmetry, allowing for a wider gate opening. Pear/HMS: Specialized oversized offset-D's used in belaying. These are usually the heaviest carabiners.