Vintage Pfizer Desk Thermometer Pharmaceutical Drug Rep Promo Diabinese Rare

Vintage metal desk thermometer or paperweight from drug company Pfizer advertising the pharmaceutical brand Diabinese (chlorpropamide). This shows the current F temp and has a corresponding chart of C temps. Heavy metal casing, probably aluminum. Not exactly sure how this works (ie if it’s liquid glass technology or not) but it does seem to be accurate. At low temps the number shows in dark blue on black background so harder to see, but a lighter color as it gets warmer. Super rare item! Excellent vintage condition. A tiny paint splatter on the back.