4.5mm ER20 GUHRING Collet Sealing Washer For Coolant Pressure Up To 150 Bar, 4.5mm - 4.0mm Sealing Range Collet Sealing Washers Are For Use With Coolant-Through Cutting Tools And Standard ER Collets in Conjunction With Sealed Collet Chucks Which Use IC/ER Collet Nuts Specifically Designed For Use With Collet Sealing Washers. The Washer is First Installed Into a Special Recess Inside The IC/ER Collet Nut, Then The Collet is Installed Into The IC/ER Collet Nut as Usual. ER Collet Sealing Washers Are to be Applied For Tool Shanks Matching The Sealing Washer Nominal Size And 0.5mm Smaller, Down to the Next Size Sealing Washer in the Series. - For Example: to Seal a 3.17mm (1/8\