What size notched trowel should I use to install Schluter-DITRA and Schluter®-DITRA-XL?

For DITRA use a 1/4" x 3/16" (6 mm x 5 mm) V-notched trowel, 5/16" x 5/16" (8 mm x 8 mm) V-notched trowel, or the DITRA trowel, which features an 11/64" x 11/64" (4.5 mm x 4.5 mm) square-notched design, is recommended. For DITRA-XL, use a 1/4" x 1/4" (6 mm x 6 mm) square-notched trowel or the DITRA-XL trowel, which features a 1/4" x 1/4" (6 mm x 6 mm) square-notched design. Mix your thin-set mortar to a fairly fluid consistency (but still able to hold a notch) and solidly embed the membrane into the fresh mortar with a float or screed trowel. It is good practice to periodically lift a corner of the membrane after embedding it in the thin-set mortar to check the fleece for full coverage. Consult the Schluter®-DITRA Installation Handbook for complete installation instructions.