ETHYL MENTHANE CARBOXAMIDE, 1R,3R,4S (1R,3R,4S-WS-3) is an enantiomer of WS-3 that is characterized by a high physiological sensation of "cooling" with no side effects such as burning, stinging or tingling. In the case of WS-3, the suppliers often do not specify optical purity, but it was indicated, in general, that compounds in the all equatorial form (like menthol) are preferred and that WS-3 with the 1R,3R,4S form (like (-)-menthol) should be optimal in cooling aspects.