These Bubble Balls are ideal for any Steampunk project. The pack contains 2 Bubble Balls one is blue non flashing, whilst the other is RGB flashing. The size of the balls are 52mm long (aaprox) including brass fitting at the base. The brass fitting is 15mm in diameter. The pack comes complete with 2 x 9 volt battery terminals. You can run both off one battery or make 2 projects. An unusual addition to any project.