Mog-3861k. Wt = 10.59g. Diam = ~24.3mm. NB mark on reverse
Photo from Amit Mehta

Wt = 11.58g. NB mark on reverse
Photo from Oswal Auctions, sale 47, lot 171

Wt = 11.40g
Photo from Todywalla, sale 55, lot 422