White Mountboard conservation grade, cut with a 40 degree bevel to an aperture size of your choosing.
Only one aperture allowed, for multiapps send us an email. 
Please supply the dimensions of the product before adding to the checkout. 
We recommend you make the dimensions at least 2mm all round smaller than the image.
We do not take responsability if the measuraments supplied are not the correct size. If you need assistance, get in touch.