fox caller

Hello, For sale is my Helion GC500 ICOtec Caller with remote it has the UK calls uploaded, The only negative is the remote antenna has come loose this is my 2nd antenna it's on, replacement ones are available from Rob @ BestFoxCall and last one was FOC. Served me well with the various calls...

I've never owned or played with one them speaker fox caller thing. I'm interested in getting one but too many option with function I am not sure about. Could you guys please advise me on what functions is a must have and recomend me one. (Preferably a budget one unless if it is really worth...