Cast Iron Flat Top Grill Griddle for Blackstone 17 inch Table Top Griddle with Back Grease System, Replacement for Blackstone 17" Portable Grill, Come with Accessories Kit

I see there is an add on you can buy for 17" Blackstone. Maybe can lead you to the size you want. https://www.amazon.com/Griddle-Blackstone-17-Replacement-Accessories/dp/B0CL3TLV98