NYLON CORNER KEY
A quick learner from Warrington PA says:
November 7, 2014
Hello, this is a brown corner key that is about 1.125" on each side and goes in a storm window that holds glass. I can't find a source to order a few that I need to replace.
Dave from SWISCO responded:
November 10, 2014
The corner in your photo looks like our 95-226, but the locking tabs are different. You might have to use either our 95-131 or 95-002 corner keys. These type of corners keys lock a little different, but I have used them as a replacement in situations like yours. See if they match up to your dimensions.