The Parallax RFID Reader Module is a 125 KHz RFID reader.
Designed in cooperation with Grand Idea Studio, the Parallax Radio Frequency Identification (RFID) Reader Module is the first low-cost solution to read passive RFID transponder tags. The RFID Reader Module can be used in a wide variety of hobbyist and commercial applications, including access control, automatic identification, robotics, navigation, inventory tracking, payment systems, and car immobilization.
There are a variety of transponder tags that come in different packages. Each tag has a specific range that is within 10% of the given distance for each type of tag. The reason for the 10% is due to environmental conditions and RFID modules.