Pack of (3) Heavy-duty Black Plastic Hinges in Matte Finish When ferrous metal won't do (think boats or other exterior applications) and you don't want brass, try these thick, heavy-duty black plastic hinges in a matte finish. Measure 2-1/2" tall with a 3/16" dia axle and approx 3/4" wide wings. They have (4) 5/16" dia mounting holes and fold from nearly flush to 270 degrees.