Sika Pro Select Backer rod is 3/4 inch closed cell compressible backup material. It is inserted into a joint to control sealant depth and to prevent 3 sided adhesion. This low density polyethylene foam is ideal for glazing installations, expansion joints, window and door perimeters, copings, and pavement joints. Resists oil and most other solvents. Available in 3/4 in. dia. x 20 ft. long per package.