A pair of wooden Nio, guardian deities, is displayed here. The larger-than-life size heads would, of course, have originally been joined to colossal bodies.
Nio are muscular deva kings (vajradara), twin manifestations of Indra which guard the temple gates, one on each side. On the right, mouth open, the Nio speaks the syllable "ah"; on the left, mouth closed, the Nio speaks the syllable "un." The first and last syllables of the Sanskrit alphabet, when spoken together, symbolize the whole of existence (Om).