ANTI-SLIP TEES: In contrast with the cleat/mesh system, the Optigreen Anti-Slip Tee system transfers soil load down the roof to a structural parapet or fascia at the bottom of the roof slope. The system consists of two interlocking T-shaped plastic extrusions: the lower one follows the slope of the roof and the upper one crosses the slope of the roof. The lower tees are spaced approximately one meter (40”) apart and the spacing of the upper tees varies from 10” to 50” depending on the roof slope.