500/500/500
Most companies are now authorized for and train/ check for 500 RVR take-off's.
The reason for this is that 500 RVR equals 150 meters. 150 meters is the minimum authorized take-off from foreign airports that measure in meters rather than feet. There are no airports in the US that allow for a take-off less than 600 RVR but we need to be authorized to 500 RVR to be able to to go down to 150 meters. RVR values this low only measure in even numbers such as 400, 600, 800, etc. therefore you will never see 500 RVR except in training or checkrides.
BTW: 600 RVR is 175 meters...