Brompton brake lever designs have evolved through the years. The clevis, or the bracket that holds the cable head (a.k.a "nipple") have also changed. For safety reasons, older levers with open clevis must use cables with longer nipples (10mm in length). Newer levers (~2009 to 2013) with closed clevis can use cables with either long or short nipples. The newest design (post-2013) can only use cables with short nipples.