How to Tell BMW Key Frequency 868mhz, 315 mhz, 433mhz?

Ordered some CAS4/FEM BMW 868MHz keys, actually I need 315MHz, so here comes one question ” How to distinguish 868MHz keys,315MHz key and 433MHz?”.

Judging by experience:

for me in EU. 90% of cas4 is 868mhz
90% of fem/bdc is 433mhz

Fact:

Not exactly – for 433 you have to specify if you need it to work for FEM or you need it for CAS4. They are not compatible like on 868 and 315 mhz.
This is only for 433mhz. And I heard there is a way to distinguish them by the exact MHZ they are working on:
– if it is 433.9mhz then it should be key for CAS4 system which has EWS4 level of security;
– if it is 433.2mhz then you can use it only on FEM/BDC system, which is also called CAS4+ with EWS5 level of security.

Here comes BMW CAS4+/FEM/BDC 315MHZ key

from http://www.vvdishop.com/wholesale/4-button-smart-key-315mhz-for-bmw-cas4-fem-bdc.html