What were mousetrap shoes?

They were shoes from the 1950's early 60's, manufactured by several different companies one of them being Thom Mcann. To close them you used the "Mousetrap" contraption, a spring-loaded clasp that snapped in place, also leading to the shoes also being known as Snapjacks. Highly prized in the Rockabilly circle owing to the fact that there are several photos showing them being worn by Elvis, Carl Perkins and Gene Vincent. These shoes have recently commanded several hundred dollars a pair even in poor condition due to their rarity and their popularity on the Japanese market. Jubilee a Japanese company recently made a retro version but had only a snap to secure the shoe and not the real "Shu-lok" mechanism.