I'm a handyman and need a source for BiltBest window seals?

I'm a handyman in Pennsylvania and run into customers who have homes with BiltBest windows from the 1970's, 1980's, 1990's and the 2000's .. most are BiltBest Clad Units, either the Challenger Double Hung BiltBest Windows or the Pro-Clad and EClad Casements. I am always seeking the correct OEM style weather striping but am uncertain what to purchase. Some aftermarket stuff just does not fit right?

BUY WEATHER STRIP ONLINE HERE: http://www.biltbestwindowparts.com/catalog/7

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