Bought this mount for my Montana 600 unit. First impressions are that this is robustly constructed if quite expensive essential assessory. The suction cup binds well and there is full but nicely resistive movement of the ball and socket allowing either dashboard or windscreen mounting. Clipping the gps unit in and out is easy. Built in speaker is integrated into the lower rear of the clip and gives off an acceptable level of sound, the volume level being controllable via the gps itself. Only thing to note here is that to get voice directions from the gps, it needs to be powered via a cigarette lighter socket using the cabling provided, unless you fancy using headphones! Without this arrangement you will only get bleeped proximity alerts. Feels a bit old school when noting my aged TomTom 510 satnav has an integrated speaker on the unit itself which doesn't need cabling to work. Maybe its a necessary compromise given the dual nature of the Montana but did surprise me.