1.4mm White Core Acid Free Mount Board
If you know the outer size but your aperture size is not listed , just purchase the correct outer size and on payment screen leave note to seller (make your you save note to seller before completing sale)
The mount aperture inside is bevel cut at a precise 45 degree angle
The mount outer edge is a straight cut at 90 degree angle
Custom mounts with single or multi aperture available
All mount apertures are cut slightly smaller than image size so your image don't fall through the aperture window