ArtToFrames 17x23 Regular Plexi Glass for Picture and Poster Frames. (Clear) Plexi Type: Regular Plexi Glass. (FRAME NOT INCLUDED) Plexi Size: 17x23. Regular Plexi Glass is a great upgrade from standard styrene which provides added protection and crystal clear clarity for your print. Fits 17x23 Frames. As measured from the back of the frame; Not the visual part in the front. Standard indoor-framing protective material #Partial UV protection for prints exposed to sunlight #Scratch resistant