TUSA M1001 Freedom HD mask with Freedom Technology. It is a single lens mask with an incredibly wide field of vision. TUSA M1001 mask boasts a 180 Rotational Buckle System, which allows it to fit a variety of face sizes while maintaining a low profile. 180 degrees Rotational Buckle System. Large frame with minimal internal volume. Five-position strap angle adjuster for micro-adjustment. Round-edge skirt. 3-D mask strap.