Perko Clam Shell Ventilator Stainless Steel 2in x 2in. Perko Clam Shell Boat Ventilators are built with a polished stainless steel finish allowing you to show-off your boat's beautiful material. You can choose between chrome and stainless steel and both finishes combine to create a luxurious feel. The Perko 2" x 2" Polished Stainless Steel Ventilator requires either a 4 or 6 screw size depending on the model and finish you choose. There are two different sizes to choose from: 1-5/8" x 1-1/2" or 2" x 2". Features of Perko Clam Shell Ventilator Stainless Steel 2in x 2" Material: Stainless Steel Finish: Polished Base Dimensions: 2" x 2" Opening Height: 9/16" Opening Width: 1-1/8" Package Contents: Perko Clam Shell Ventilator Stainless Steel 2in x 2" Perko 0315DP2STS: Clam Shell Ventilator Stainless Steel 2in x 2in