3 way crossover

so...
i've been running up front the hertz energy esk 165 system witch is 2 way ...last week a friend gave me a pair of mids (hertz energy EM 100)so what i need now is a 3 way crossover witch i need to get.. because im new to this stuff can any one suggest me a 3 way crossover and also what i have to know for looking one out???
the rms of the system will be 125 watt rms... 250 max
and also will be going passive..


thanks in advance