Janser Green Box Concaved Blades RWS007A. These concaved blades are made in Germany for Janser of high quality steel boxed in 100s and sub divided in pastic dispensers which makes them popular with carpet fitters and floor layers because this keeps the concaved blades safe in the tool box. These fit theJanser Coloured knives. they will also fit most standard pattern knives includind all Dolphins and Dolphin style knives.