A coupling for joining pipe segments together is disclosed. A cantilever excitation device is provided with a cantilever, a cantilever holder for holding the cantilever, and a piezoelectric vibrator attached to the cantilever holder. The projections communicate between the sidewalls also providing structural integrity to the photopanel and allowing for thinner sidewalls and increased light transmission therethrough. The selection means is used to select a tip from a plurality of lancet tips which have different lengths and make only this tip available for use in the lancing process. For example, the techniques may be used in an engine that performs transmission control protocol operations for received packets for a host.