Q-Link pendants are unnecessary to the qigong practitioner and there are many similar products on the market, many of which are counter-productive. If you must indulge yourself, a number of Chinese qigong masters do make available qi-energized objects for maintaining the integrity of your qi-field and preventing the intrusion of qi modulated with incompatible messages or signals. A couple of examples that come to mind include
https://www.sslpage.com/dadaocha/shop/product_info.php?cPath=22&products_id=142&osCsid=5b6695c9176ebfd868c13828a7afc5b9
and
http://www.qinway.org/qigong_object.htm
