CRS Rail Adapters for Bottom Rails easily attach to 1-1/2 inch Schedule 40 Stainless Steel Posts to provide for attachment of 1-1/2 inch (38.1 millimeter) diameter Cap Railing when used as the Bottom Rail of the CRS System. Unlike the Top Rail, only this size can be used as the Bottom Rail. Use our Cat. No. 32629 Metal Contact Cement to achieve a secure and permanent bond.