Hi Peter, you can buy the studs from ebay, about £6.99 with a tool to put them in with.
I think you get about 30, but I just put three at the front of the boot, and three at the heel.
It helps a lot when stepping out of the river onto a grass / muddy bank.
It has worked a treat for me.
Don't you just love Orvis, God bless them I say.
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"A glint of sun has warmed the air,The flies will soon hatch out, To lure and tempt from their deep lair, The bonnie speckled trout."
SKB tackle supporter. I love Furled Leaders.