This white-colored top perfectly fits the original 18 x 20 ft. frame you already have and looks just like the top that came with your initial purchase. There is a slight overhang included in the design, and the drawstring attached to the cover ensures a snug, secure fit. This top is ideal for people who have experience damage to their original top, whose top has gotten worn or frayed over time, or who just want to keep a replacement on hand to prevent any down-time should an accident occur.
There's no need to spend a lot of time lamenting Murphy's Law as it applies to your favorite outdoor shelter. You can replace the top very quickly, very easily, and with minimal investment. If you're looking for a cure for whatever ails your favorite shelter's top, you may very well be looking for a King Canopy 20 x 20 White Drawstrings Cover.