Lasco 2 Pack 1-1/2" O.D. Reducing Washer for 1-1/4" O.D. x1-1/2" Slip Joint Connection. It is made of durable rubber and is designed to reduce the size of a 1-1/4" O.D. tube to fit a 1-1/2" slip joint connection. This washer is ideal for plumbing applications and is easy to install.