I saw my first OV-1 butane lighter in Brigade Quartermasters - Catalog #10 back in the 1980s. (These were contract overun pieces.) Shortly after that my friend gave me my first issued OV-1 lighter.
You can imagine my excitement when I discovered later that there was an earlier Air Force butane lighter - the SRU-21/P lighter.
Note: This photo is copyrighted
Now interestingly all of the butane lighters were assigned the same NSN: 9920-00-999-6753 from the Viet Nam War until the Army finally cancelled the OV-1 lighter.
Note: I was never able to find the contract numbers for the various lighters and the "SRU-21/P", "OV-1" and "Hybrid" designations are mine so that I could distinguish between the types.
From research for an ebook that I helped my friend put together on these unique pieces of SRU equipment - I determined that the SRU-21/P lighter came first. It was made by a sole source for the Air Force. Then at some point the Army started using the OV-1 fire starter Butane in both the Army Vest Kit and the OV-1 RSSK kits. Then there was a third company that made what I call a hybrid lighter - it was small like the SRU-21/P but it had an OV-1 type cap.
The SRU-21/P lighter was made by K-Whit tools and apparently when the Air Force cancelled the SRU-21/P lighter in 1979 - the principles of K-Whit tools filed for a US patent. IMO - the SRU-21/P fire starter butane is the best - though it is the more difficult to refill.
The Army continued to supply the OV-1 lighter in the OV-1 RSSK kits up until the NSN was cancelled in 1985.
Unfortunately most people only have experience with the faulty "hybrid" fire starters that were made by a third company in CA from ~1980 to ~Jul 1981.
You can also see a definite drop in quality between the early issued OV-1 lighters and the later issued OV-1 lighters.
These butane fire starters were never intended to be refilled or re-flinted by US Army ALSE personnel during the Viet Nam war. They were replaced by ALSE upon failing inspection. I have not been able to obtain the information as to whether or not the Air Force performed these depot level repairs in Viet Nam. After the war - this policy changed and TC 1-62, Aviation Life Support Equipment (ALSE) reflects the change in budget constrants - the lighters were not considered disposable.
The SRU lighter ordered by the Air Force as a replacement for the starter fire NP3, M2 was a well made quality piece of gear. In my collection the SRU-21/P lighters do not leak. I can not say the same thing for the late model OV-1 lighters nor the Hybrid lighters.
More photos to follow.