Quoted from delt31:I just recently got a pin with stern hd glass and have it next to invisiglass. Absolutely no difference. I've seen pdi as well. Would say it's the same. For me it's whatever it's cheaper if the three..... So stern
No offense, but I would be more inclined to believe http://www.pinballnews.com/learn/glass/index.html who tested both Inivisiglass and PDI and found Invisiglass to be inferior, over a guy who looked at them in different environments and thinks they are the same.