Did you know anyone still uses these things? Where I grew up it was grey/red Clay soil... with lots of rocks. These things were punishing to use. You could beat them until they bend...then the first good wind the fence lays down like that 40' cedar tree that took down part of my house last night.
They tend to run out of level when they hit an obstruction--rock, root, power or gas line... They make a wobbly fence. I don't like these fence spikes--and will never recommend them.
get my point? It's not smart to pound a piece of sharp steel into the ground around a house with utilities coming in nearby. I am amazed and astounded that no one has been killed by a hydro strike in damp ground with one of these things...
You too can have poly spikes on the top of your fence... since it's decoration and removable it might just be the thing to add 6" to your fence and send a message to that miscreant sociopath next door.
I have actually heard that the main reason people use them is because they can't stand the idea of local cats and other rodents walking along them. Maybe we should put this one in the "Insanity Folder".
With all the liability issues I just can't see these catching on in North America--any more than Screens in Windows would catch on in the UK.
But I like these fence spikes-- I really do.