About Infrared (IR) Thermometers: Distance to Spot Ratio – Sper Scientific Direct
Infrared Thermometer,High Temp Thermometer Pyrometer -58℉- 2732℉ (-50℃ to 1500℃),30:1 Distance Spot Ratio,AP-2732 Non-Contact Digital Dual Laser Pointers Flashlight IR Temperature Gun【NOT for Human】 - Walmart.com
Amazon.com: BTMETER BT-985B Laser Temp Gun Pyrometer, -58~2480℉(-50~1360℃) High Temperature Meter, 16:1 Distance Spot Ratio Industrial Infrared Thermometer Tester for Furnace, Smelting (NOT for Human Temp) : Industrial & Scientific
Infrared Thermometers explained
Metris IR100-1 Long Distance Dual Laser High Temp Infrared Thermometer (100:1 distance to spot ratio)