Amarine-made Stainless Steel Clamshell Vent/Wire Cover Clam Shell Vent for Boat - 07724s Clam shell vents 12mm (H) x 44mm (W) x 40mm (L), th=0.6mm Stailess steel Amarine-made A = 1/2" B = 1-3/4" C = 1-5/8"