Friendly Reminder: Professional installation is recommended. If you're doing it yourself, remember to always wear protective gear, use the correct tools, and install properly. Valuable Package: The package includes 4 pulleys and 2 yokes, which can be used as 2 fixed pulleys plus 2 sliding yoke wheel pulleys, meeting your various needs. Comes with 4 screws and nuts, saving you time searching through your toolbox. High Quality: The garage door pulley system is heavy-duty, with a 200lb load capacity for doors up to 400lb. Durable steel construction, center ring with 9 ball bearings, and pre-lubricated at the factory for smooth gliding. Function: This 3in garage door pulley kit is designed to repair or replace damaged parts of your old, worn, noisy, and jumping doors. Provides a quiet, smooth, and pleasant door opening/closing experience. Compatible: The 3in pulley has a 3/8 hole and 3/8 cable groove, which adapts to the most common garage doors and accepts a maximum 5/16 diameter draw cable or straps.