Standard 20# Propane tank (like you get at a Gas Station Tank Exchange). The following dimensions on the model match the tank I have to 1/16": Overall Height & Width; Bottom Ring Height & Width; Protective Collar Height & Width; Valve Height & Valve Knob; Bottom Ring on the model is exactly like the one on my tank. The protective collar on the model is ALMOST exactly like the one on my 20# tank. The only difference being that my model collar has 2 handles and 1 'hole', while the tank collar has one handle and 2 'holes'. I cut&pasted that collar from my 40# tank, made a couple small mods to match my 20# tank, and just figured some 20# tank collars probably have 2 handles and 1 hole anyway.