Cokin A123S is a B2 blue half filter with a soft transition to the Cokin A system (size S). Size S is the smallest series of Cokin filters designed for compact cameras.
The Cokin A123S filter allows you to color part of a photo. One half of the filter is neutral, the other half is blue. The transition between them is smooth, so you will not see a clear color border. Cokin filters are mounted using a holder (holder), which is attached to replaceable mounting adapters, with diameters that can be adapted to your lens. System A (size S) is recommended for use with compact cameras with lens filters or amateur video cameras.