Blades that replace wheels on inlines...
https://www.ebay.com/itm/Stainless-Steel-Ice-Skate-Blade-Roller-Ice-Skates-Shoes-Blades-Sharpener/223458315744?hash=item3407274de0:m:m2FXuxYpXdU_dynqeKKkvoQ (https://www.ebay.com/itm/Stainless-Steel-Ice-Skate-Blade-Roller-Ice-Skates-Shoes-Blades-Sharpener/223458315744?hash=item3407274de0:m:m2FXuxYpXdU_dynqeKKkvoQ)
It's certainly another case of buyer beware. At first, I thought "What a clever ideal. Does it really work?". Then I became suspicious when they claimed stainless steel blades. The blades come in two colors, gold and blue. That treatment is typical of anodized aluminum, not stainless. I'd bet that they are aluminum, and not stainless as claimed. Aluminum is MUCH softer than stainless, and very prone to damage and wear.
I got a chuckle, so in that respect, it was worth the look. But I wouldn't buy any.