Jetglas was a line of residential water heaters produced in the United States from sometime in the 1950s until 2008. As of March 2015, they appear to be out of production.
There is very little information available about Jetglas online, but old advertising indicates that they began selling water heaters at some point in the late 1950s.
The most current source of information about the company appears to be the D&B Distributing Company of Silver Spring, Maryland. Although this company has a website indicating they are an authorized Jetglas dealer and providing information about Jetglas serial numbers, its last update occurred in 2008.