From the Encyclopedia of Vietnamese Music at PBwiki.
Each pair of sinh tiền consists of two long rectangular sticks known as lá phách. One is simply a single piece of wood with a sawtooth pattern along one edge, whereas the other is actually a clapper made of a long stick attached to a shorter stick by leather or a hinge. The longer stick lies on top and has coins loosely attached by nails or screws on the open end, whereas the middle region is lined by another notched pattern. Various sounds can be made by clapping, shaking, running the notched edges together, etc.. Sinh tiền finds its most prominent use in court music and ceremonial music.