These amp corners are the 2 leg version with the wrap around front lip. They measure 1.6" x 1.6" and have an internal radius of 1/2". Designed for 3/4in thick cabinet material.
I also have these in the 2 leg without the front lip, and also in the 3 leg version, and also in black.
These are sold in four piece sets- most cabinets will require two sets, but note that many cabinets require different style corners on the front and rear.
(Click the thumbnail pictures above to see an enlarge view).