The tailpiece is connected to the end button with a high quality tail gut. The tailgut length is adjusted to bring the vibrating string length and afterlength to the optimal specification.
Most instruments are set up with a single fine tuner on the tailpiece that matches the pegs, endbutton and chinrest. On many student instruments though, a composite tailpiece with fine tuners on all strings may be used to simplify tuning, and to reduce weight.