The rubber washer is compatible with the Boss Bidet Brass T Adaptor. The Boss Bidet Brass T Adaptor and Rubber Washer are included with the Boss Bidet Bold.
Adaptor and Rubber Washer Size By Region:
7/8 inch - USA, Canada, Central & South America
3/8 inch - Europe
1/2 inch - Asia, Middle East, UK, Australia, New Zealand