Abstract: Cylindrical foam body with a central cavity, whereby the foam body is formed by a curved flexible foam strip of which two opposite ends are fastened together, whereby the foam body has a height, whereby the strip 2 has a length, a height and a width, whereby after forming the foam body the longitudinal direction of the strip 2 is the height direction of the foam body, whereby the foam body has an outside and an inside. The foam body is provided on its outside with two or more grooves that extend over the height of the foam body and which only cut into the foam body over a part of the distance between the outside and the inside.