Product details:

All our garage door torsion springs meet the association of door and access control system manufacturers standard rating of 18,000+ door open and close cycles. Both the winding and stationary cones are professionally installed for safe operation. - Surface coated black to make sure springs wont rust in the open air. Do NOT attempt to install springs or hardware yourself unless you have the proper tools, reasonable mechanical aptitude and experience, and upper arm strength. Extension and torsion springs, along with attached hardware, are under extreme tension at all times. All tension must be released from springs before any work is performed. - IMPORTANT:Please purchase after confirming that the outer diameter, wire diameter and length are totally the same as the original product. - Even a little change in size can result in different performance,so please check carefully before purchasing to avoid waste.