αF SMD resistor coding
The product in the photo is Gravity: Analog Current to Voltage Converter. 

As for the components (\$\alpha F\$) in the question, I've checked the schematic, they are shown as R2 and R5 but no details have been given.

Most likely they are protection elements: could be a fuse or even a resettable (PTC) fuse (I'd prefer the latter, though, since the product is designed for 4-20mA.). They can even be from German company Alpha-Therm.