Reference system is a complete, ready-to-use kit that allows you to update existing catalog racks to display single sheets. Nonglare protective sleeves offer two-sided viewing and can be easily removed, photocopied and changed. Modular tongue and groove design fits all Master references racks. Retrofit kit includes 12 sleeves (24 view facings), 12 snap-on custom indexing tabs, and 3" wide solid metal modular section. Design includes heavy-gauge steel base and nonskid feet.