This line of 3-prong extenstion clamps are constructed of pressure die casted zinc alloy and are chrome plated. Clamps open to about 3", have a recommended maximum grip size of about 2.25", and feature double keyed spring-type adjustment screws. Available with an extension rod 8.25" long, 5/16" OD, with an overall length of 12.75", or with a boss head clamp that can swing freely and is lockable at any angle up to 360°, and can be used with rods up to 19mm. Recommended maximum working temperature is 80°C for the PVC version, and 280°C for the silicone sleeve version.