ProVantage is a mortar free Glass Block Installation System consisting of horizontal spacers and an 8 in. vertical spacer. Spacer are siliconed in place to the Glass Block and ProVantage anchor or U-shaped perimeter channels are used to fasten the glass blocks to the project's sides, sill and header. Depending on the application, the joints can be finished with either grout or glass block silicone. Each component is sold separately. This horizontal spacer is for use with 3" thick glass block. For use with Basic profile glass block - NOT for use with Pegasus style glass block.