http://www.airsoftparts.ca/store2/in...oducts_id=2365
That rail (airsoft design seem to mimic the mounting style of the one on the picture ... the holes system is a bit different ... on you kwa RM4 (if you have the scout version) there is a part of the outer barrel that you can unscrew (right after the delta front sight) removing this part would allow you to put an overbarrel silencer to mimic the integrated silencer of the honey badger ...
To do that mod you will need to change the delta-ring for the barrel nuts that come with the rail system and the rest do not require mutch if you have more question ... feel free to ask