Whatever you like. Start with a combination of the following items:
=== Transceiver ===
# [https://en.wikipedia.org/wiki/General_Mobile_Radio_Service#Frequency_chart GMRS ] (or FRS) - Basic General Mobile Radio Service, no licence required, all channels used by airsoft -- any manufacturer (Motorola, Cobra, etc)
# Programmable UHF and VHF - programmable UHF and VHF, may need licence if programmed for high power output, you will need to program it for GMRS channels -- Puxing 888
=== Push to Talk Switch ===
# Tactical -- Cavalvy, Ztactical, etc