The Wooden Sounding Block in front of the Sima on top of Cittalapabbata Hill
Because there are so many pillars and a rear view photo would either put me off the cliff, or poke my eye out, I have included two pictures to show what the wooden hollow tree drum looks like from two angles.
Taken with my tablet. This particular drumming was for the preparation of the Patimokkha meeting (recitation of the rules). It can be heard clearly all the way from my kuti. The drum is struck 15 minutes before every meditation session and at 3:30 AM for waking up.