IDEAL APPLICATION: This add-on helps reinforce and stabilize a narrow wood or vinyl screen door, preventing it from sagging or warping.USE: Attach the turnbuckle diagonally and simply rotate the center dial to bring the two halves of the turnbuckle together.DURABILITY: Quality and durable construction ensures reliable everyday use on your door.READY TO INSTALL: Easy to install and adjust.CLEAN SUBTLE LOOK: High-quality finish allows it to blend in perfectly with your door and frame. Wright Products 42″ turnbuckle is ideal for narrow wooden/vinyl doors that are out of square. Attach the turnbuckle diagonally and simple rotate the center dial to bring the two halves of the turnbuckle together.