These are the Stübben Steeltec gag cheeks. 

These gag cheeks are of high quality Stübben leather in combination with black nylon ropes. The rings and buckles are of stainless steel.

The rings are not stiched on to the nylon ropes but fixed with a rope loop only. Just slide the rope down through the gag bit, then loop the rope over the ring. No more screws or stitching.