An infrared thermometer comprising: a body portion comprising one or more snap-on features (6,9), an electronic circuit that is configured to measure intensity of an infrared signal received from a patient and convert the infrared signal into an output that reflects the patient's body temperature; a probe switch in communication with the circuit configured to signal the electronic circuit that a probe cover is being installed; and a second switch that is in communication with the circuit configured to signal the electronic circuit that an attachment mechanism is being installed; a probe portion comprising an infrared window that is configured to accept the infrared signal received from the patient; and an attachment mechanism, the interior of which is a generally circular hollow bore shaped for being coupled to the probe portion, having a proximal end for coupling to the probe and a distal end comprising retainer notch (55a, 55b) to accommodate a probe cover; the attachment mechanism comprising a hollow bore at the distal end, one or more snap-on features (51, 56) at the proximal end to engage the one or more snap-on features (6,9) of the body portion, a pin at the proximal end for interacting with the second switch, and a probe cover detection mechanism comprising a bar slidably mounted in the attachment mechanism and extending from the proximal end of the attachment mechanism to the distal end of the attachment mechanism, the slidable bar having a first end configured to engage with the probe switch, and a second end configured to engage with the probe cover; wherein when the attachment mechanism is coupled to the probe and the pin interacts with the second switch in a first position, the circuit converts the infrared signal based upon a first calculation, when the pin interacts with the second switch in a second position, the circuit converts the signal based upon a second calculation, whereby the circuit accounts for signal loss due to the probe cover according to the probe cover switch. a body portion comprising one or more snap-on features (6,9), an electronic circuit that is configured to measure intensity of an infrared signal received from a patient and convert the infrared signal into an output that reflects the patient's body temperature; a probe switch in communication with the circuit configured to signal the electronic circuit that a probe cover is being installed; and a second switch that is in communication with the circuit configured to signal the electronic circuit that an attachment mechanism is being installed; a probe portion comprising an infrared window that is configured to accept the infrared signal received from the patient; and an attachment mechanism, the interior of which is a generally circular hollow bore shaped for being coupled to the probe portion, having a proximal end for coupling to the probe and a distal end comprising retainer notch (55a, 55b) to accommodate a probe cover; the attachment mechanism comprising a hollow bore at the distal end, one or more snap-on features (51, 56) at the proximal end to engage the one or more snap-on features (6,9) of the body portion, a pin at the proximal end for interacting with the second switch, and a probe cover detection mechanism comprising a bar slidably mounted in the attachment mechanism and extending from the proximal end of the attachment mechanism to the distal end of the attachment mechanism, the slidable bar having a first end configured to engage with the probe switch, and a second end configured to engage with the probe cover; wherein when the attachment mechanism is coupled to the probe and the pin interacts with the second switch in a first position, the circuit converts the infrared signal based upon a first calculation, when the pin interacts with the second switch in a second position, the circuit converts the signal based upon a second calculation, whereby the circuit accounts for signal loss due to the probe cover according to the probe cover switch.