RXD stepping motor unit is exceptionally quiet. Tamron 70-300mm F/4.5-6.3 Di III RXD Lens (Model A047). It achieves the world's smallest size and lightest weight, coming in at 5.8 in. The lens also incorporates the RXD (Rapid eXtra-silent stepping Drive) unit, a high-speed precision AF drive system that is remarkably quiet.
