Abstract: Apparatus for supporting a mining bit in a bit holder which attaches to the rotatable drum of a mining machine. The apparatus comprises a sleeve that is adapted to be received in aperture in the bit holder. The sleeve has an aperture therethrough for rotatably receiving a cutting bit. The sleeve has a body portion and a collar which serves to prevent axial movement of the sleeve relative to the bit holder. An under cut area is provided in the body portion and/or the collar to reduce the peak amount of stress that develops between the body portion and collar. The bit holder and sleeve are constructed such that the position of the sleeve may be fixed axially with respect to the body portion by an interference fit in such a manner that it may be easily removed from the body portion.