On this side of the pond there are only a few of these in use and sales have been limited partly by the high cost and unreliability. It's a great design concept and it is appreciated why they emerged from NZ with all its remote mountain areas where alien predator species have been decimating native wildlife.
In the UK the dominant trap for use on grey squirrels is the Fenn Mark4
https://www.trapbarn.com/sss4afinal/ -
Utterly reliable and cost-effective
he Mark6 is a bigger version (6") that tackles mink and rabbits.
