Sling TV is now offering a free Roku streaming stick or a free Amazon Fire stick if you pre-pay for the first three months of the new Internet TV service. The Roku streaming stick, which connects to the HDMI port of a High-Definition TV, delivers the same number of channels (more than 1,800, including Sling TV) that a Roku set-top provides. The stick, which measures just three inches by one inch, is now available at Amazon.com for $48.89.