Related Clues:

• Golf tees, for instance
• Pieces in the game Battleship
• Pieces in the board game Mastermind
• Coat rack pieces
• Battleship markers
• Coats and hats can be hung on them
• Square ones won't fit into round holes
• Tent-securing spikes
• Square ones don't fit in round holes
• The Game of Life pieces
• Hat-hanging aids
• Lite-Brite bulbs, really
• Bass tuners
• Gets out in dodgeball, say
• Cello quartet