This is the one I have, great reviews.

https://www.amazon.com/Prodyne-126-B-Cheese-Slicer-Bamboo/dp/B000I6147Y/

I carefully screwed a small block of wood to it above the wire, so I can get a consistent 1-inch thick bar of soap cut. I also screwed a small block on the side to prevent the wire coming down pushing the loaf to the side. Works great, been using it for a couple years now.