The ones I saw at walmart run on lighter fluid.

Maybe this one is the 20th century version. Usually when batteries get warm I get worried. As long as it doesn't burst into flame it sounds great!

Down under "you also may like"...theres a Big Blue version

https://www.amazon.com/dp/B07G8679SX/ref=cm_sw_r_cp_awdb_imm_t1_e9fzFbJ7789E6