400mw should still be treated with respect, IMHO all lasers should be treated with respect regardless of the output power, helps drive in good safety habits, the last I knew the threshold for eye damage can start at or around 5mw and do not take a picture with beams hitting the lens on the camera, that will damage it, found that out the hard way, one of my cameras has about a dozen dead pixels from an accidental hit to my camera and I was a good distance away but it still did damage and here is the kill shot.
Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu