of the arms to effect fine adjustment to stretch the hat band adjustment block 20 is rotated about its longitudinal axis such rotation will produce extension or retraction of threaded rod 20 resulting in commensurate displacement of first arcuate band 16 with respect to second arcuate band 18 to remove hat stretcher 10 from hat 12 collar 80 is translated away from the ends of arms 60 62 to permit the arms to spring apart thereafter ratchet rod 24 may be translated longitudinally into the adjustment block to relieve the pressure of the hat stretcher against the headband the hat stretcher may now be withdrawn from within the hat to reinstall the hat stretcher it is placed within the hat in general alignment with headband 14 and ratchet rod is extended from within adjustment block 20 until the pair of pawls engage the formerly engaged ratchet groove to effect instantaneous engagement upon translation of the ratchet rod slight manually applied pressure may be placed upon the opposed arms to force the pawls into engagement with the ratchet groove thereafter collar 80 is slid towards the ends of the arms to maintain the pawls in place further coarse or fine adjustment of the hat stretcher is unnecessary in order to apply the same.