The Ovo-Scope egg-candler is used to identify infertile eggs in setter flats.  Removing infertile eggs at an early stage (9 to 12 days) greatly improves the air flow in the incubator and hatcher.  The improved air flow from this early stage can improve hatchability 1 to 2%. For in-egg vaccination, vaccine costs can be reduced by 10% or more because there is no vaccine wasted in infertile eggs.

In multistage incubators with corridors, the Ovo-Scope can be taken directly into the incubator and eggs candled at 9 to 10 days. The Ovo-Scope allows light to pass through the eggs but not around them, protecting the eyes of the operator. There are two manual pneumatic lifters to remove infertile eggs and a special high intensity light for extra verification.

Two people can easily candle 50,000 to 60,000 eggs per hour; one worker carries the flats back and forth from the Ovo-Scope and the other candles the egg.