Ridder Slitesterk was a popular collection for children produced by Janus in the 1930s and is now being re-launched. The garments are made in a double-knit wool quality and in CrinkleWool with its loopy knit. Both types of knits are extremely comfortable for children. The collection includes long johns/tights, tops, sweatpants, zip-up jackets, pinafore dresses and hats. The Ridder Slitesterk collection was launched to celebrate the 100th anniversary of the Janus brandname. The Janus brandname was registered in 1909.