adjustable

This style of rigging turnbuckle is designed to be easily adjusted.  When handles are extended you can tighten or loosen, when handles are colapesed they lock the turnbuckle.  These types of turnbuckles are often used as backstay adjusters and for removable inner forestays (availble with quick pins).  Trailerable sailboats and some class racers use the calibarated style for quick set ups and changing wind conditions.