boylucky:
Would you have any advice which one to select? It need to operate in EU so 868 MHz.
In the EU, its region 1, so you can use 434Mhz which will go twice as far as 868Mhz at the same power.
2 x AA Lithiums OK, 2 x AA Alkalines bad, they will be at 1.2Veachor so for a lot of their life, 2.4V supply is marginal.