While the placemat was too big for my son's highchair tray, we improvised and removed the tray and stuck the placemat directly on our wooden kitchen table. It's worked an absolute treat- my son is a thrower and hasn't been able to dislodge this placemat. Being silicone its easy to clean, a quick rinse and straight in the dishwasher. We love it!
The plate works great although the size is too large for a conventional high char tray we moved my son to eating at the table and this sorted the issue