Mirror Weight?

Finished weight painting on Arm.L for the human mesh
how can i copy that to Arm.R for the other side of the mesh?
everything is symmetrical, mesh and bones

Well the weight paint tool has a mirror function you can enable yourself (which requires your character is facing forward in front view [numpad 1] so the X axis runs from one side to the other). But if you’ve already painted without mirror enabled, try this script.