The Leviton DW6HD, DW1KD, D26HD, DW3HL and D23LP are all forward phase dimmers. They are compatible with Dimmable LED, Incandescent, and Magnetic Low Voltage lighting loads.
For applications requiring a reverse phase dimmer, please see the article How do I dim Electronic Low Voltage (ELV) or 0-10V lighting loads with Decora Smart® Wi-Fi?