These are the Fender style corners with countersunk holes and the wrap around front lip. They measure 1-9/16" x 1-9/16" and have an internal radius of .44". These are for 3/4" cabinets.
These are sold in 4pc sets! Most speaker cabinets will require 8 corners, but most will have different styles on the front and rear.
These include the matching nickel plated #8x3/4" oval head wood screws for installation as shown in the picture!