Ww2 era German Luftschutz helmet 39/21

Early one piece luftschutz helmet with liner and chin strap. Stamping is hard to read and I took pictures both dry and slightly wetting it with water, the wet shows up a little better but still hard to make out so I may be wrong on one character or so. Looks like RL2 and 39/21. Probably a pre war used for factory or HJ flak crews, these were used throughout the war as well.