The woman lays on her back, and her basin will be lifted with the man’s help. Her lover sits between her calves, crosses her legs placing her feet on his chest and then penetrates her deeply. Embracing his beloved and supporting himself with his knees and fingertips on the ground, the man can move easily both passionately and at a slow but firm pace. The intimate contact is very deep and because of the woman's position (the vagina decreases greatly in size in this position), the man can reach her cervix. For this reason, the woman can have the cervico-uterine orgasm in this position, a type of orgasm that few women can experience.
This sexual posture greatly amplifies the sexual and vital energy and therefore it is recommended both at the beginning of the amorous intercourse (in order to engage the sexual and vital potential) and towards the end, when both lovers feel the need of a revigoration of the vital force.
Source: yogaesoteric.net