Turnbuckles are used in a variety of applications and allow for easy adjustment of tension on cable, rope or chain. Because the bolt on each end has opposite threading, tension can be increased or decreased simply by rotating the center frame. When increasing tension, the bolts on either end are pulled in towards each other. Although often used in industrial applications, they may also be used around the home. One example is removing "sag" of heavy duty outdoor lighting that is constructed from thick cable too heavy to pull tight by hand (before using for this type of application, verify with the lighting manufacturer how much tension the cable can safely handle). It is also important to select the proper turnbuckle for your application based on load requirements.