Dunno if this has been posted before, please delete if so.
http://wiki.sabmagfaq.org/Site_glass_replacement
http://wiki.sabmagfaq.org/Site_glass_replacement
Yeah, i won an auction for one of those kits, but the source cited in the thread I posted is far-less. Actually, you could go to any watch repair shop & give the specs (no pun intended) for the glass & probably buy it for a few $.I ordered a kit from a guy on eBay. Came with all the instructions, glass, and new screws for the cover for less then $20. I will dig up the eBay page but if you just do a search you should be able to find it
Right at the bottom of the article it reads this:
Size needed: 16.7 mm lens of either glass or mineral glass. .8 mm thickness recommended.