This project is open to all confirmed or potential members of clade R1a-L1280, a subclade of a very large Central-Eastern European clade R1a-Z280. We encourage our members to test for at least 37 STR-markers, which in most cases should be enough to predict the L1280 membership. For more precise classification within clade L1280, we suggest ordering the most informative Y-DNA test named Big Y700.