 Tama were once made of clay, but now are most commonly wood filled with lead.The weight of the tama maintains even tension on the warp threads, and is balanced by a bag of counterweights called "omori" that is attached to the base of the braid.Modern braiders often replace the marudai with a foam disk with numbered slots that tightly grip the warp threads so that no weighted bobbins are needed to maintain tension on them.