Mid Century Modern Walter Bosse Nesting Hedgehog Ashtray Set - 6 pcs RARE SDL

1950s Walter Bosse vintage nesting Hedgehog Ashtrays 6 pcs, ranging from 4 1/2" long mama to 1 3/4" long baby on top. 3" tall all stacked together. I've tried to do my research but have seen these variously described as bronze * and * brass. They have a gorgeous patina and I have made no attempt to clean them, and don't know how to tell which they are. All I can say is these little suckers are solid, heavy, and absolutely adorable. The largest bears a faint "SDL" stamp on the tummy Please refer to Modern Vienna Bronze, update #12, as to what this may mean. https://www.modernviennabronze.com/walter-bosse-news/authenticating-your-walter-bosse-hedgehog-ashtrays-part-2-rare-models-and-marks These came from an elderly couple's attic, and that's all anyone remembers. This item was donated to the Subterranean Super Sale, and as such the entirety of the proceeds will go to one of the following organizations: https://www.bcrf.org https://www.pinkfund.org https://www.pinkribbongood.org https://equalhope.org Thank you!