Technique is also a factor. Acetylene delivers maximum BTU's close to the tip. Alternate fuels, such as propane and natural gas, deliver heat energy farther out in the flame. Consequently, you need to hold the tip farther away from the surface or material to be heated. The Little Torch will work with any fuel gas choice.
Natural gas is popluar, but, sometimes the pressure is limited.
It is very important to have sufficient pressure of fuel gas flowing through the tip. Always refer to the owners manual for correct pressure settings for the tip being used. Insufficient pressure will starve the tip, causing the tip to overheat and possibly develop into a burnback and flashback. I would recommend that you view the webpage regarding the kit and tip choices for the Little Torch. Any kit will work, but you need to decide on cylinder size and fuel gas choice.