Old Finnish army diagonal weave wool trousers, these are just like the wartime M36 trousers but they have piping of various colors on the side. Carefully remove the piping and these are pretty much like the stuff our grandparents fought the war in.
The piping color and style vary. Often the center stripe is sewn between the fabric, so it'll require some skill to remove neatly. Otherwise, these are the bee's knees with a proper high waist, suspender buttons, and waist adjustment, and what all, and THAT FABRIC. It's something you just don't see anymore - very high quality, thick diagonal wool. They used to make war stuff out of this kind of luxury fabric, Jesus Christ. Don't put these into a washing machine, brush the dirt off, and spot wash if necessary.
Sizes simply by the measured waist and leg inseam of the trousers. Measure your waist at the navel and compare. As said, these have adjustment tabs on the waist, so the size can be tightened a bit from the given measurement.
Priced according to sizes - larger ones are rare, so they cost more. All are pretty affordable for what they are, and we haven't seen too many of these in the market anyway.
Old but at least not worn in the field. While they are pretty neat and clean, there might be a few moths nips here and there. Being made in the '50s and '60s is bound to leave a mark or two...