After World War II, the Czechoslovak Army used a wide variety of foreign uniforms of British, American, Italian and especially German origins. In an attempt to unify the appearance of the soldiers, a new uniform was introduced as early as 1945 with the designation M 45. However, the existing uniforms could continue to be used until the end of 1946. After the introduction of uniform 21 in the early 1950s, the existing M 45 uniforms were designated as uniform 20. The cut of the jacket was largely based on the pre-war M 30 jacket. However, the number of buttons was reduced from 5 to 6, which allowed the jacket to be better worn with an open collar. Other changes were the ventilation holes in the armpits, the fastening of the lower side pockets and, of course, the material. The new colour of the uniform was supposed to be khaki, but in reality various woollen fabrics of Czechoslovak and German origin were used.