We call this the Kartcoin, or the 'coin for keeps'. This handy token comes on a carabiner clip and can attach to a customers' key chain. That way, they always have the right coin available to do their shopping!
Having seen these systems all over Europe and Canada we saw the definite need for the Kartlok here in the USA. Abandoned and stolen carts are a significant cost to businesses which in turn costs consumers. They are an unsightly problem in our communities and waterways.
These cart locks are good for businesses, good for customers, and good for the environment.