Up for sale is a 3/4 FULL Acetylene B Tank .This tank holds 40 cuft of acetylene gas. I used this tank for my plumber's torch but it can be used for oxy/acetylene torch welding too. This tank is 3/4 FULL, but you just have to bring it to Praxair when empty (or any other gas outlet) and exchange it for a full one (just pay for the gas- not cylinder deposit). This tank is owned outright- so no more rental fees, etc. No place selling used tanks for exchange will sell them this low- eg. Places sells them for $289 + tax empty (and they are reused just like mine). Buy mine for only $300 3/4 FULL! ***watch out, some tanks are all rusted out or expired!***