Six inch round stainless steel Talk Thru has offset holes in front and rear to allow natural voice transmission. Gaffco Model GS-24 Talk Thru is available as interior or exterior model (specify)
It fits glass from 1/4" to 1 7/8" thick.
Denote glass thickness of window when ordering talk thru.

Requires 5" diameter hole.

Class I or III bullet resistant.