The Schluter®- DITRA-TROWEL, KERDI-TROWEL, and DITRA-HEAT/-DITRA-XL-TROWEL feature square-notched designs to effectively install DITRA, KERDI, DITRA-XL, DITRA-HEAT, and DITRA-HEAT-DUO, respectively.
 
DITRA-TROWEL features a 11/64" x 11/64" (4.5 mm x 4.5 mm) square notch