1939 Lockfast Zipper

While digging through some old notions for a button I found this little gem. It looks like a Hookless/ Talon zip but is a maker named "Lockfast" Note the holes ready for rivets to secure the bottom stops. There is no mention of Lockfast in "Zipper, An Exploration in Novelty" by Robert Friedel. The Patent drawings are pretty neat for this zipper. 

Earlier, Max Keissler designed this picture hanger:

I've photographed this vintage zipper on a yard of late 19th C indigo dyed cotton shirting with an oversize 'herringbone' print. Here's some pics of the fabric with label: