The mouth is filled with metal, so it doesn't wear down and is easy to maintain. You can use it almost continuously until the blade is gone without having to adjust the base. The shaving width is 27mm. In the photo taken from directly above, the slope on the right side of the mouth is difficult to see, so I took another picture tilted to the right. The back iron seems to be old, as it has a hole. Perhaps it's a rivet hole from an old iron bridge. The back iron also fits well, so it's also a good one. I've cleaned it to remove the dirt, but it's an old base, so it's less likely to warp. Even with new ones, the blade can rust if it's old, and in severe cases, it can become stuck and the blade won't come out. This one also had some rust, so I've removed the dirt and wiped it with oil, so please rest assured. Please refrain from price negotiations, except for bulk purchases. Also, please consult in advance for bulk purchases.