I just picked these up yesterday. They are in perfect condition and dated 1938 and 1941. They also have the original cardboard tubes with the name Cherbourg written on them and one cover made from parachute material. I am guessing that is where they were found by a Canadian soldier who brought them home. I have a lot of ordinance and it is very rare to find anything from WWII in this condition.
Here is description I found on Anthony G Williams's web site.
This was the second of the 20mm cannon cartridges developed by Solothurn in the 1930s, and is known as the "Long Solothurn" round. It proved far more successful than the 20x105B, being primarily used in the highly successful FlaK 30 and 38 AA guns which were extensively used by German forces in WW2 (and remained in service in some nations for decades after the war). It was also used in the KwK 30 and 38 light AFV guns, and in the Solothurn S18-1000 series anti-tank rifles.
As well as being used in these German and Swiss weapons, it was used in the Finnish Lahti L39 anti-tank rifle and L40 AA gun, and in the Italian Breda M35 and Scotti cannon. A very wide range of ammunition was developed for this gun, including M-geschoss shells and Pzgr 40 tungsten-cored AP.