The Thomas Glass Rectangle Cover is a rectangle slide cover slip used to hold a slide specimen in place and protect it from accidental contact with the microscope lens. The corrosion-resistant glass cover is used in dry or wet mounts for high-resolution microscopy. The thickness of the slip is precision controlled for uniformity and the slip conforms to Interim Federal Specification NNN-C-001434A.The rectangular cover is used in dry or wet mounts for high-resolution microscopes in medical, hydrological, and pathological laboratory settings.

Thomas Scientific manufactures lab supplies, equipment, chemicals, and instruments for scientific research. It is a registered contractor for the United States Federal Government. The company was founded in 1899 and is headquartered in Philadelphia, PA.