Access Control Cards, or access cards or RFID access cards, these cards are available with different frequencies based on application and use. Generally, access control cards are classified into three
A : Active, Active RFID access card, offered with the built-in battery.
B : Biometric, Biometric access card, based on fingerprints.
C : Hybrid or Combo cards, Combination of UHF & LF or UHF & HF, LF & HF
P : Passive, Passive RFID access card that work on showing to an assigned reader, these cards are widely used being less expensive
The major classification of RFID cards is based on frequency for active and passive cards. 

The widely used passive and hybrid cards in access control systems are 

25KHz Low frequency cards (LF) [Nundprox K]860~960MHz UHF + LF 125KHz [Nundprox KU]
13.56MHz High frequency cards (HF) [Nundprox M]860~960MHz UHF+ HF13.56MHZ [Nundprox MU]
860~960MHz Ultra High Frequency (UHF) [Nundprox U]860~960MHz UHF + HF13.56MHz + LF125KHz [Nundprox MKU]