PRO ART 2-PLY BRISTOL PAD - Acid free, Pro Art Bristol is a Rising #1 sulphite, tub-hard sized, artists quality, true two-ply pasted, drawing bristol board with a neutral pH for the best possible archival characteristics. Both sides of the sheet are esigned for pen, pencil and markers. Both surfaces will handle erasure and reworking. Xerox compatible. Acid free. 12 sheets/pad.