The Bel-Art Products 445570000 microscope slide holder tray is made of plastic for durability and holds up to 12, 25 x 75mm (1 x 3") microscope slides (sold separately). It has inclined ribs to hold the slides securely standing on their ends.Bel-Art Products manufactures scientific products, including labware, testing equipment, and safety supplies, under the Bel-Art and Scienceware brands. The company, founded in 1946, is headquartered in Wayne, NJ. Research, industrial and healthcare professionals rely on SP Scienceware for their sample handling needs. Sold worldwide, Bel-Art and H-B Instrument brand laboratory supplies include over 5,000 items from safety wash bottles to fume hoods, thermometers, racks, desiccators, hydrometers, ice buckets, scoops and spoons. Custom calibration services, plastic molding, specialty coatings and wire manufacturing are also available. Wilmad-LabGlass brand laboratory glassware complements Bel-Art and H-B Instrument with over 7000 items including NMR and EPR consumables and specialty glassware, as well as custom fabrication for individual glassware, glass repair services and OEM glass parts. SP Scienceware is a division of Warminster, PA based SP Industries which also include SP Scientific laboratory, thermal management, and pharmaceutical production equipment and SP Ableware aids for daily living.