990 Sliding Door Superior structure for high performance The ′′990′′ is a high-performance aluminum sliding door engineered for the most demanding residential, commercial and institutional applications. Here is a product you can specify for wind and rain battered high-rise or low-rise buildings. Independent certified tests, no water passed the interior plane of the ′′990′′ when subjected to a simulated rainfall with 55 miles per hour wind. The standard 1-3/4′′ tubular stiles and heavy-duty interlocks mean superior structural integrity.