DIY 'Backless' Frame

What are frames like these even called? I have seen them being sold everywhere so I wanted to make some myself. If you know what they are called then let me know in the comments, cus I had no idea what to call this... 
If you do not want to glue the glass down but you do not like the small things at the back (and what are those called? haha) then either get a frame where they are super small or cut as much off as you can without cutting everything so it will not be able to hold it together. I found the frames at a thrift store where you can get them super cheap in the same size.