This is our medium tubastrea measuring 4x2.5x2.5 inches high. These are made of a durable, flexible and nearly unbreakable UV stable polyurethane composite safe for all aquariums. Many colors to choose from. Pictured here is the standard two tone yellow/orange color. All of the neon color options will glow under black light and actinic led lights!! Thank You and enjoy! Call or email us anytime with any questions at 1-888-637-6598 or oceanaquaria@gmail.com