WARNING: Torsion springs, extension springs, and related door hardware can cause serious injury or death if not handled and installed properly.  Professional installation is recommended.  Do NOT attempt to install springs or hardware yourself unless you have the proper tools, reasonable mechanical aptitude and experience, and upper arm strength.  Read and understand all instructions before you begin work.  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.