Review on Arrow Home Products Dish Wand Sponge Refills - Snap-on Replacement Sponges, 3 Packs (6 Pieces Total) - BPA-Free Sponge Replacement Head by Kathy Jones

I had a Butler pen and was out of refills - tried it and it more or less fits. See my photo - Butler on the left, Strelka on the right. The Arrow sponge doesn't snap to the bottom (instead the bottom of the grip rests on the white piece of plastic on the bottom), but it fits perfectly in width and works well. I'm glad I no longer waste plastic on another pen. Just make sure your pen has a rectangular holder (if they are different designs). I've been using it for a week now and I really like these sponges. They seem to be of better quality than foam rubber with scrubbers.