In yesterdays pinball news post : https://www.pinballnews.com/site/2018/10/17/american-pinball-visit/
it says:
American Pinball source their playfields from two different suppliers, and there are a few telltale differences between them, such as the type of pattern used to diffuse light in the inserts and the hardness of the wood.
So.. which manufacturer has better (harder) playfields ?