Inserted between twinwall polycarbonate panel and greenhouse girt. Sold in multiples of 100 only. The EPDM Spacers are 1" sq. x 3/8" thick and feature an adhesive backing.
The spacers they say are designed to be used in conjunction with the glazing bar system. The problem is the spacer is 3/8+ thick and the glazing bar is only 1/4 tall resulting in a hump wherever you put them under the panel on a girt.
This spacer is definitely needed when building a twin wall polycarbonate greenhouse. The spacer I received are built to last.