UNIBLOCK BU FLAGSTONE VINYL J-BLOCK | The UniBlock, universal J-Block mounting block is used to install exterior electrical outlets, water faucets, light fixtures, mailboxes, house numbers, and doorbells. Richwood mounting blocks are built to withstand the toughest weather and retain their color and beauty over the life of the home. They will not chip, crack, or split. They are simple to install and have a 2-piece design that easily adjusts from 1/2" to 1-1/4". This feature allows for easy installation over many siding choices, including insulated vinyl siding. Limited lifetime warranty