While the optical coating extends to the edge of every Semrock filter, the clear aperture will be less than the transverse dimensions for each filter. 

For unhoused, round filters, the clear aperture is guaranteed to be greater than 85% of the outer diameter.  For square and rectangular parts, the guaranteed clear aperture will be greater than 80% of the filter's transverse dimensions and is elliptically shaped.  The clear aperture of a housed filter is dependent on the size and thickness of the housing ring.  All filter specifications are guaranteed only within the clear aperture region. 

Specific information can be found on the Specifications Tab for each individual filter.