Probably just straight butane. I have some of those cans also, use it on hot summer days. Has to say Isobutane to be a mix.
Jerry
web site:
http://thescrr.com/
The Butane I use doesn't say on the canister what the mix ratio is, but I found Sun Flame brand in an 8 oz can, made in Korea, priced at 2 for $3.00 at Osco Drug.
I stopped at the main Cabela's store(big sporting goods chain) in Sidney, NE to see if they had any isobutane mixture cans. Looked in the fuel section and found the butane cans I got there last year but no isobutane mix. I asked and she took be over to another section and they had the cans there. It's an 80/20 mix in an orange can. $9 for the large cans. Brunton is the brand name. Looked on brunton.com and they did say it is a 80/20 mix. The Primus cans I had gotten before say 70/30, but I have to mail order those and pay a Hazmat fee on top of the can price. Cabelas is building more stores around the country so you might check them out if you cannot find the mixture in your area.
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