It is a cotter pin extractor. I'm in commercial roofing, low slope (flat) This is one of the most important tools we use when inspecting or installing a single ply roof. It's more commonly referred to as a "Probe" or Seam Probe" It allows us to run a seam and find voids which could lead to a leak or is a leak source. The roofing system manufacturers sell their own probes for around $15-25 ea. but for about $4.00 ea I buy 4-5 a year. They're like lighters, you always lose them and when you need one.... I also use it to illustrate in this case a hole in the membrane for inspection reports. Photos tell a story and an owner see's the defect much better. Now before someone say's it, yes it is easy to put the hole in yourself and claim that's the problem. In the language of the Biz... We don't kick the flashings, That's for jacklegs, We fix the flashings.