The cost of the investment to ISX of the four installations is said to have been $2.95m (cost - i.e. investment)The return from the installation of those four installations (from two) is said to have been $1.06m (revenue - i.e return) in 2019. Based on this, I would have projected the return on investment would be ~ 37% or payoff in 3 years. This is a bloody good investment by anyone's measure.