Engineer Calculation Pads are excellent for engineering classes and labs. Smooth, green-tint, 15 lb. paper is plain, except for printed outline box on top of sheet, and has 5-square-per-inch grid layout printed on back of sheet. Back grid shows through to front as dimensional guide for drawings and layouts. Sheets are glued along the 8-1/2" top edge and three-hole punched along the 11" binding edge so it can easily fit inside letter-size, three-ring binders. The 34 point chipboard backs add stability.