Mammut Carabiners Workhorse HMS Screwgate Carabiner Screw Gate Grey One Size 20400256015021. Its size allows user-friendly operation even when wearing gloves. The opening width and volumes are large enough to accommodate several ropes slings and knots. It is ideal for use as a central carabiner for anchoring as it is particularly robust and durable. The screw locking is easy to operate even in icy or dirty environments. The key lock nose allows easier clipping and unclipping without snagging. An orange marking indicates when the carabiner is not closed.