Great for cutting in boxes in cabinets or islands. Use your reciprocating saw like a jig saw.
I have not used these yet, but they'll be one of my future purchases so that I can make adjustments in ceramic or glass tiles crowding my boxes.
I go through a lot of these cutting plaster lath walls and ceilings. Old houses eat these things up.
You get 50 here for about what you'd pay for a three pack at one of the box stores.