Remember the days were computers were not really that accessible and your school maybe just had the 1 BBC Micro that you got to look at twice a year to play Defender on. In those days a pencil or pen was more commonly used and when mistakes were made, you just rubbed out the error and carried on writing.
These Keypad erasers make you realise why computers are needed as it's far quicker to hit the backspace key then it is to grab your eraser and make a mess of the paper. This set of erasers has the arrow keys and the Insert, Home, Page up, Page down, Delete and End.
Availability is unknown at the moment, but they should be available soon over at Present Time.