In addition to HSC Haltern-Sythen, 18 other teams from 7 different countries do play in Boys 21. They are divided into 2 different groups, whereof HSC Haltern-Sythen can be found in Group 2 together with Lugi HF 1, HV Dynamico, Täby HBK, IK Baltichov, Kärra HF, Sokol Velke Mezirici and Schiffdorf TV. HSC Haltern-Sythen also participated in Boys 21 during Partille Cup 2023. They reached the 1/4 Final in B21 B-Play-off, but lost it against HK Ankaret with 13-23.