Jeep and A4 Caps
During WWII the Army issued two types of knit caps- the M1941 wool knit cap (aka jeep) and the A4. They are basically the same cap except that the former had a small visor. Both can be worn alone or under the steel helmet. Personally I find the A4 preferable- the sides are a bit longer so they cover the wearer's ears better.
We offer two styles of each- we make some in our own shop with 100% wool knit from Minnesota. The other is an imported version, in a 50/50 wool/ polyester blend. Both are made with tubular cloth- there is no seam.