Grout Prism Liner (GPL) utilizes a thin corrugated paper based upon the patented engineered design in Deslauriers’ GSB. The proven slotted surface allows moisture to pass through to the block. Grout Prism Spacer (GPS) is manufactured from a rigid, non-absorbent plastic and is non-reactive to grout constituents. The Grout Prism Spacer is durable, reusable, and easy to clean.