Do you need to control access to your secret lair? Why not install an RFID alarm system?
This RFID reader module will allow your .NET Gadgeteer project to identify 125kHz RFID tags.
Two tags are even included so you can test it out.

Microsoft .NET Gadgeteer is an open-source toolkit for building small electronic devices using the .NET Micro Framework and Visual Studio/Visual C# Express.
This module is designed to quickly and easily integrate into any .NET Gadgeteer project.

Dimensions: 37.5mm x 37.5mm

Includes:

• RFID Reader Module
• Gadgeteer Cable

Documents:

• Tutorial
• Gadgeteer Site