Review on Tempil 28019 Surface Temperature Indicator, 1 Indicatometer, 250°F by Jamie Behm

It's so bad I don't know why this product is being sold. The marker is inside the metal housing. The collet at the end, which must be loosened to remove the marker, is tight and does not rotate. I smashed the case to get the marker but found it didn't even mark aluminum. It's totally useless. I guess they eventually had a usable product because they wouldn't have gotten very far with crap like that.