These are excellent quality steel door hinges. 135 gauge steel. (1/8" thick) The ball tips are 9/16" diameter. The corners are square. Available in 2 sizes and 4 finishes. Door Hinge with Ball Tip - 3.5"x3.5" - Brass $9.98 Door Hinge with Ball Tip - 3.5"x3.5" - Nickel $9.98 Door Hinge with Ball Tip - 3.5"x3.5" - Brushed Nickel $9.98 Door Hinge with Ball Tip - 3.5"x3.5"- Oil Rubbed Bronze $9.98 Door Hinge with Ball Tip 4"x 4" Brass $10.98 Door Hinge with Ball Tip 4"x4" Nickel $10.98 Door Hinge with Ball Tip 4"x4" Brushed Nickel $10.98 Door Hinge with Ball Tip 4"x4" Oil Rubbed Bronze $10.98