I think Granite shield is probably a good sealer.
But I could name a whole page full of good sealers at a more reasonable price.
A lifetime guarantee they offer- but am not sure of their track record.
Not sure about their system but recently had a client tell me that their marble was totally etched after a year having granite shield.
They knew that the granite shield wouldn't stop etching so they were fine with that.
Before they had the tops refinished they called granite shield to see if they would reseal the tops after refinishing as they got a lifetime guarantee.
Granite shield told them if they get their tops refinished they would have to pay to have the granite shield reapplied.
Guess its better to use it on granite like the name implies.
So many slabs coming in resined today not sure it would be a big seller.
People do buy it however so who knows.
I have a friend who sells and installs it-He is in Connecticut if you ever wanted to speak with him.