These are also a webber style strap as there is a nylon loop at the top that goes through the stirrup strap ring and then the adjustment is made with a Conway buckle. There is an advantage over the T-bar straps because the T-bar doesn't fit through the slot of many english irons. But these do work best for people who run their stirrup straps under the flap as the stitched overlap of the nylon loop to the granite biothane strap can rub the outside of the flap.
Also best for less strenuous riding as the nylon loop can move sideways and put torque on the front or back of the stirrup ring if the rider's legs aren't in a shoulder-hip-heel alignment.
Best configuration is to have the Conway point away from the rider's leg which points it forward, also away from the horse, but there is a snug keeper to hold everything in place. For people who regularly change stirrup length for students or Ride&Tie partners, arrange the top layer of the strap on the post side of the Conway for easiest changes.