hi, want to ask question about eyeball lighting.

not sure if anyone's house is using such lighting, wanna ask if buy eyeball as per screenshot on the first one(using shopee as example), do we need to buy the casing as well? what's the purpose of the casing actually? does putting casing actually make it look more pleasing/better?

the thought of having casing + the eyeball itself is costing me alot of money haha