You can call them bridges, bridge connectors, or strap connectors. Call them whatever you like, but at Emmaline Bags, they are Strap Keepers because they like to keep your strap in line. These are gorgeous, and high quality. With the 1/4" (6mm) height, you should be able to get 1 or 2 layers of strap underneath, depending on how you are using them.
Inside Measurements:
To be used with 1" (25 mm) straps.
( NOTE: The actual width inside the keeper is 15/16" (24 mm) at the base and 7/8" (23 mm) near the top of the bridge.) For stiffer fabrics that will not fit inside this measurement, consider making a strap 7/8" (23 mm) wide.