IRT(Infrared Thermometer) is an instant magic, but when you take it from outdoor to indoor (or from one room to another room). You have to wait 30 minutes. "30 minutes" is absolutely not "instant". Most of IRT are plagued by such flaw.

By Many-year-experience in high precision clinical infrared thermometer (in EN12470, Error due to 10degC thermal shock must be less than 0.2degC!)
Finite Element Analysis of heat transfer; ZyTemp had overcome this barrier.

A simple test , according to test method described in in EN12470 Paragraph 7.6 Testing for compliance of accuracy under changing environmental conditions.,
clearly show that our ZyTemp TN105 out perform the competitor's model, which usually has a price tag much higher than TN105.

Error of M model can reach 1.6degC and require 30minutes to stabilize, while TN105 is only 0.7degC and stabilize in 7minutes.

A typical error of reading is not a simaple figure, it's a function of Tobj (object temperature) & Tamb (ambient temperature)
Because Infrared Thermoemter is a "Relative" measurement instrument. (It compare the Tobj against Tamb)
So, the error has a minimum value when Tobj ~ Tamb,
that is when you measure something close to ambient temperature.
For ZyTemp, this minimum value (dTabs) = 0.15°C / 0.27°F ,
usually, our competitor is larger than 0.2°C / 0.36°F

At higher or lower temperature, there is a Gain Error , usually 2%.

Q: since the spec is "+/-2°C or 2%", so IRT is most accurate at Tobj=0°C?
A: No, as described as above, IRT use a "Relative" measurement, so IRT is most accurate at Tobj=Tamb,
In other word, when you pointing the IRT at a "near room temp" object, it will be very accurate.

Q: I can calibrate my IRT, by point it to a wall (25°C)?
A: No, even the Gain run away, the IRT still will show 25°C, you have to use a "Temperature Different From Tamb",
for example 0°C or 50°C
0°C is the most available temperature "standard", for ordinary user.