The phrase "glass casing" refers to the protective cover made of glass that encloses or covers an object, usually to allow for visibility while providing protection. Full definition
A sleek white, open space and accessories on display in glass cases make you feel as if you're in an art gallery rather than a bridal shop. (brides.com)
To the right is the cashier area for placing orders for hot drinks such at tea or coffee or glass cases with pastries, brownies and loaf cakes. (www3.hilton.com)
For example, there are no fancy glass cases displaying prepared foods with a staff member standing by to dish up your $ 20 piece of wild salmon. (health.com)