What is the significance of using a hand mudra during meditation practice?
It is the union of posture, breath, and focus; or asana, pranayama, and mudra.
Surya Ravi Mudra is practiced by touching the tips of the ring finger and the thumb together.
The cosmic mudra tends to turn your attention inward.
mainsa (flesh), matsya (fish), madya (wine), maithuna (sexual union), and mudra (mystical finger signs) - probably the most degrading cult ever practised under the pretext of religious worship.