Practice those return shots to help with your tennis game with this training device that lets you practice alone almost anywhere. Just fill this 8" x 8" x 2" plastic base with water to weigh it down, place it on the ground then activate the system to launch a tennis ball that's connected to the base by a long elastic cord. Includes two balls, each with an attached cord. Makes a great gift for tennis friendly activities and events. Blue base and yellow tennis balls. Add your school, sports team, organizational or company logo or message to customize.