Pistola de espuma en aerosol

The worst part of the whole spray foam in a can system is having to use the can upside-down. The can will absolutely be in the way while you're trying to spray or cause you to lean the can over to a point where it doesn't want to spray the foam. But, if you have the 40" gun, you can basically reach anywhere you need to without the can being in the way nor tilting too far and not spraying foam.
This is one of those times where spending more money upfront will save you a ton of time/effort while performing the job. The pic is an 8ft high sill plate bay that I was able to spray without the electrical wires being an issue, I didn't need a ladder, and the giant 24oz inverted can sitting on top of the gun never got close to the ceiling with the 40" reach.