Stamp of today is an adjustable wrench ('skiftnyckel' =adjustable key), a Swedish invention patented by Johan Petter Johansson. I love these old drawings with their letters and lines for the hollow parts you can't see from the outside.  I like the design with the postage inside the mouth of the wrench too, 2 kronor 70 öre. growing up in Sweden I didn't think these wrenches were such a big deal, but I learned better after hearing from the experts. 


You can see on the picture how these developed from the ones made in Enköping, Sweden, in the 1880s to today's wrenches sold by Bahco (still in Enköping). They are nearly the same! (Click on photo for larger version.  Photo by Theresemk and from Wikipedia. )