Key fob
Wearables & cards
What is it?
An RFID key fob is a small, durable token designed to be carried on a keyring. Inside the plastic housing is a small RFID transponder – typically LF (125 kHz) for legacy access control or HF (13.56 MHz) for modern systems. Key fobs are the second most common access control credential after smart cards.
How it works
A small RFID transponder is encapsulated in ABS or epoxy and shaped into a compact form factor (typically 35–45 mm). The housing protects the transponder from daily wear. LF fobs use a simple coil antenna and read-only chips (EM4100, T5577). HF fobs use MIFARE or DESFire chips with encryption and mutual authentication.
Use cases
- Building access control
- Parking garages
- Gym and club membership
- Apartment intercom systems
- Equipment checkout
Pros
- Extremely durable – survives years on a keyring
- Compact and convenient to carry
- No battery required
- Low cost for basic LF models
Cons
- Very short read range
- LF fobs often lack encryption (easily cloned)
- Limited memory compared to smart cards
- Not suitable for tracking applications
Specifications
| Power type | Passive – powered by reader signal |
|---|---|
| Frequency | LF (125 kHz) or HF (13.56 MHz) |
| Read range | LF: up to 10 cm; HF: up to 5 cm |
| Lifespan | 10+ years |
| Price range | $0.50–$5.00 per unit |
| Environmental rating | IP65+; designed for daily carry and abuse |