Due to popular demand, we've created a free, ad-supported version of Chronos Gas Swiss Army Knife. This has an unobtrusive banner ad at the bottom of the screen. If you want an ad-free version, you can purchase the normal version from the Play Store. Carry out Gas Rate Calculations and save them for future review. Calculate BTU / Kwh requirements for rooms. More tools will be added in future and it will always be free.