Our ring book bottom headed work sheets offer extra convenience, with perforated top & bottom areas that detach as needed. Durable! Green-tinted 20 lb. stock. 13 columns, 40 lines. Easy to use! Perforated for easy detachment at top & bottom. Prepunched. Accommodates 3-ring binders, prong fasteners, partition folders or columnar sheet binders. Surface allows ultra-clear entries & easy erasing. 12 pads per box, 50 sheets per pad.