Wheaton staining dishes 

These mix-and-match components offer greater flexibility in meeting your requirements. This staining dish accommodates 16, 20 and 30-slide racks. Holds slides sizes: 3" × 1" (75 mm × 25 mm), 3" × 1 ¹/₂ " (75 mm × 38 mm), and 3" × 2" (75 mm × 51 mm). Manufactured from soda-lime glass.
Approx. Inside Dimensions: (118 mm L × 88 mm W × 70 mm D)