In the context of scientific equipment in India, “glass slave” is likely a misspelling or misinterpretation of a glass sleeve or 3-inch watch glass.

A very common 3-inch scientific item frequently listed by Indian wholesalers.

• Purpose: Used as a surface for evaporating liquids, weighing solids, or covering beakers.
• Specifications: Often 3 inches (approx. 75mm) in diameter and made of transparent flint or borosilicate glass.