The stable hadronic bound states in a hidden new non-Abelian gauge sector provide interesting candidates for strongly-interacting Dark Matter (DM). A particular example are theories in which DM is made up of dark pions which set the DM relic abundance through self-annihilation. One of the simplest realizations is Sp(4)c gauge theory with two Dirac fermions. https://www.vacuumdoctores.shop/product-category/new-pressure-washer/