Штифтунг Варентест
SRAM manufacture the i-Light hub dynamo. The D7 series is available for both rim and disc brakes while the D3 series features several of rim brake varieties. In a 2006 review by the German Stiftung Warentest, the efficiency at of a D1 series i-Light hub dynamo was 66%, 10% better than a SON-28.