The wings are 6.5 inches apart. My bread knife is just under 8 inches long. I can only move the knife a little over an inch each stroke or the blade will fall out of the slot. I got it mainly for sandwich bread which doesn't come close to filling the area between the wings. The slots are about 1/8 inch wide so there could be up to a quarter inch difference in the bread slices depending on how the knife was held on the two cuts.I know its not a precision instrument and I like it but that is what stood out on its first use.It works. Not 100% intuitive, but easy to use once you fiddle with it for a few minutes.I bought this bread cutter with the hope that our bread can be cut and sliced evenly. The item was out of stock for the longest time during lockdown, so we had many unevenly cut bread during that period. I jumped at ordering when it was back in stock again. I was wondering what the narrower and wider version were, but couldn’t find the answer. I asked the community, but got a reply that there are different thickness as slicing guide, that didn’t answer my question. I don’t know how I ended up with the wide version, it was a bad purchase for the following reasons! ??The first picture shows how much wider the bread slicer is compared to my loaf from my breadmaker. Because of that, it’s really hard to slice the loaf without holding and securing it against the side.Secondly, my bread knife kept getting stuck while slicing! I can’t extend the knife forward too much without it knocking against the side of the slicer! Do bread knives come in longer lengths? That I’ll really need to find out!Thirdly, I’d recommend using a chopping board under the loaf as slicing bread on the slicer itself would only leave marks on the base (see picture 3). Wished I’d listened to some of the reviewers here, but guess we were just too anxious to get the slicing going during dinner time. Feeling sad that the beautiful board is now scratched.4) The manufacturer should come up with another piece of board to keep the bread steady by securing it at both ends and not just at one end. This way, the bread would probably not move that much during slicing.5) Lastly, check out the picture of my cut loaf. The top one is my last piece, I couldn’t hold it secure enough to slice it into two. Oh well, I guess it’s better than cutting free hand! At least we can still use a sandwich maker with decently sliced bread now!It cost me a bomb having this sent to me. I had to use a shipping forwarder and all and now I can’t return it. I wish they’d mention in the listing that the width refers to the width of your loaf. If you have a wider bread pan, get the wider version. If your pan is smaller and narrower, get the narrow one. Having said that, please make sure you measure first before buying!This was very easy to assemble and take down just follow the instruction. It has a spring that holds the side in place, the support board that comes with it keeps the bread at the size you want to cut it. It has different widths you cut it to make it easy to get real thin bread or to slice it the same size as store bought bread. The top curves so you can easily see where it changes width to make it easier to get the right size cut each time.The slots lined up nicely with each side to make it very easy to get the knife in for an even cut. The support bar has stops on both sides to support the slicer and keep it in place. I found that I was using the back board to place the end cutting from the opened end which is a mistake. You want to use the board as the guide to the size you want but cutting your bread closest to the board. If you look at the picture of the sellers where the board is to the left you should make your cut in the lines next to the board not at the open end. Depending on the size of your bread you may need to hold it against one side to keep it in place. Take what you cut out and move the bread up against the support board etc. This really works for any size of bread from small (if you hold it to the side as you cut it) to a bigger size. It holds a little bit bigger size width than a store size loaf of bread.Do not limit yourself to just bread you can use it for so much more such as pound cake or anything that will fit into the slicer. You do not even need to limit yourself to the pre size cut guides you can skip every two slots to make it wider for to dipping or garlic bread.I had a little problem with mine the back plate end had the holder part broken off on opening it. I contacted the seller with a picture of the problem they shipped me a replacement right way. This was done in a timely fashion and very easy to deal with the seller. I am very pleased with this product as long as you use the guides above you shouldn’t have a problem.