He is beating the Semantron (a wooden board made of heart of Maple or Beech) with two wooden mallets to summon the monastics to prayer.

Where there is a metal Semantron, it is customary to strike it after the wooden one has been played. The Semantron is sounded every midnight for night offices (Midnight Office and Matins) this is done by the candle-lighter.

The Semantra are usually suspended by chains from a peg in the proaulion (porch of the catholicon) or outside the refectory door, or on a tree in the courtyard.