Specifications

While specifications vary from device to device, they all fall within a range of what is considered acceptable. Here's the specification from a FlashTree fingerprint scanner.

Supply voltage: DC 3.8 to 7.0V
Backlight color: red
Operating current: <60mA
Peak current: <85mA
Fingerprint image input time: <0.5 seconds
Window area: 15 × 17mm
Matching method: Comparison method (1: 1)
Search method (1: N)
Characteristic file: 384 bytes
Template file: 786 bytes
Storage capacity: 100
False Acceptance Rate (FAR): <0.001% (default)
Refusal rate (FRR): <1.0% (default)
Search time: <500 ms (1: 100 average)
Host interface: UART (TTL logic level)
Communication baud rate (UART): 57600(default)
Size:44.320.217mm

And here's the specification for the Adafruit fingerprint scanner.

Supply voltage: 3.6 - 6.0VDC
Operating current: 120mA max
Peak current: 150mA max
Fingerprint imaging time: <1.0 seconds
Window area: 14mm x 18mm
Signature file: 256 bytes
Template file: 512 bytes
Storage capacity: 162 templates
Safety ratings (1-5 low to high safety)
False Acceptance Rate: <0.001% (Security level 3)
False Reject Rate: <1.0% (Security level 3)
Interface: TTL Serial
Baud rate: 9600, 19200, 28800, 38400, 57600 (default is 57600)
Working temperature rating: -20C to +50C
Working humidy: 40%-85% RH
Full Dimensions: 56 x 20 x 21.5mm
Exposed Dimensions (when placed in box): 21mm x 21mm x 21mm triangular
Weight: 20 grams