These are perfect for the job they fit my favourite pencils, so hence they reason for purchase, not to big so as to make the pencil top heavy, for anyone who does a lot of pencil work they are really handy.
I used something like this in other countries, but could not find these anywhere in the UK or ROI. They are brilliant, one less thing to keep up with in a pencil case, the hole is deep enough that it doesn't tear the part that goes over the pencil tip (which makes it a handheld rubber/eraser from that point on), and they last 2 mos. each with my writing-mad 10 year old...unless he gives them away to friends, which he does regularly. Sigh. The good news is they are inexpensive to replace!