These screen printing hinge clamps are made of zinc alloy, chrome-coated surface, they are durable and rust resistant.The clamps feature two holes that you screw directly into your workbench and wide-wing thumb screws to secure your frame (screws is not included).These clamps also feature positive locking for perfect registration.The screen print butterfly clamps are used for fixing screens when printing. It can hold all wood or metal screens from 0.5 inch to 1.8 inch (12 to 45 mm) thick, Height: 3.3 inch (85mm), Length of Clamp: 2.4 inch (60mm) They are used to secure your screen frame to a table or work surface, easy to install and positive locking for perfect registration.For starters, new beginners to learn how to screen printing. The screen printing hinge clamp is the fastest way to build a printing press.Material: Zinc alloycolour: silverPackage Contents:2 x Butterfly Hinge ClampOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.