Deluxe Action Domes™ include slip-resistant dipped rubber rims for safer step and stand-on balancing. Accessories include Hurdles, Arches, and Posts all sold separately. Segments snap together, are interchangeable, and are the strongest blow-molded segmented pieces made for play! Domes are 9” dia. x 4” H. Deluxe Action Domes are great indoors or out, but add-on items are best suited for indoor play.