Abstract: A brush comprises a sleeve, a cap member, a brushing member, and at least one elastic member. The sleeve has a first end and a second end. The brushing member is movably received in the sleeve at the first end, while the cap member is firmly coupled to the sleeve at the second end. The elastic member is disposed between the cap member and the brushing member so that a portion of the brushing member protrudes from the first end of the sleeve.