Maybe some of the posts have read are old. The directv site lists the B-Band converters needed for HR20 receivers. Solid Signal where I am looking at getting my equipment from also lists B-Band converters for HR20. Nothing mentioned for HR21. I can't even find a mention of the swmslimline dish on the directv site. I purchased 2 HR21 receivers, a slimline dish and the Zinwell WB68 mulitiswitch. I just need to figure out if I will need the B-Band Converters as well now so I can order it all at once.