Chi Sau is the most important part of the system. Chi Sau is not a form of kata. Chi Sau is not a form of sparring. Chi Sau is the bridge between techniques from the forms and real fighting. The forms are always the same. Chi Sau is free development. Every session is different.
Storm door installation will cost $200 to $400. It will take a professional half a day to a full day to install a storm door. The length of time it will take depends on the complexity of the installation. If the installation is straightforward then it will take less time, and therefore, cost less.
1 Installation can bring the total cost to $1,000-$5,500 or more.  Expect costs to double for impact-resistant patio doors (sliding, French-style or single hinged) that can withstand hurricane-force winds. Mike Davidson Construction in Florida estimates that installing a 9' impact-resistant sliding glass door costs about $3,700, compared to $1,800 for tempered glass.