An "entry fob" is a small device, like a keychain, that is used to unlock and access certain places or systems, such as doors or cars, by transmitting a signal. Full definition
Alpha Shield Premium Keyless Go - Aluminium Box for Car Key Holder RFID Blocking Case, Car Key Safe Box, Car Keyless Entry Fob Guard Signal Blocker Faraday Tin (amazon.co.uk)
3 X Car Key Signal Blocker Case, MONOJOY Keyless Entry Fob Guard Signal Blocking Pouch Bag, Antitheft Lock Devices, Healthy Cell Phone Privacy Protection Security WIFI / GSM / LTE / NFC / RFID Blocker (amazon.co.uk)
The car key signal blocker case stiching with RPF which stop thieves amplifying your fob signal and opening car, stop your keyless entry fobs from being remotely accessed. (amazon.co.uk)