500x400mm external with centrally positioned window to fit the largest square possible on A3 paper, actual size 280x280mm. White core. Acid free. 5 sheets per pack.

Images on this site are a representation of colours available. Actual colours may vary. 

Our Snow White textured Square picture window mounts have a nicely proportioned aperture and a slightly deeper base than top. The acid free board from which they are cut is an off white, acid free, neutral shade board with a white core and is a framing industry standard.

• 280mm Square aperture - 280x280mm aperture, which fits the largest square which can be acheived from an A3 sheet. The aperture is positioned so that the mount has a slightly deeper base than the top.
• Aperture position - 60mm from left & right - 95mm from the top and 125mm from the bottom.