A feedback device, for use by a golfer to indicate head movement during a backswing. The fractional divider includes a permutation network including a plurality of phase input terminals and a plurality of permuted phase output terminals with a plurality of propagation paths extending therebetween. The surround includes a seal attachment flange for attachment to the seal, and may have a faux muntin pattern formed integrally therewith. The enables the patch to readily conform to a complex 3D surface such as a portion of a patient’s face to ensure efficient transmission of ultrasound energy to a desired area of treatment. In other embodiments, the cover can be a slideable or moveable low-profile sleeve or metal cover. The rake surfaces of the cutting protrusions are located on longitudinally opposite end surfaces of the cutting insert.