Platinum Mechanical Pencil Eraser Refill - Size CA - Pack of 5

Pros: Fit perfectly, easy to remove, cheap. Also, I noticed that these erasers fit the Ohto Promecha, which is very convenient.

Cons: Don't last long, can't utilize the entire eraser due to design (even if you try to slide the eraser up the metal case as it wears down, it will not stay in place).