VivaRhythm Boom Series Drums deliver a lower overall tone with outstanding projection. The synthetic shell features a rubber bottom to prevent slippage or scratching and is shaped to allow air to escape from the shell. This creates low fundamental tone that resonates fully. The BOOM SERIES pre-tuned synthetic heads give a robust attack. Each drum is stackable inside the other for easy storage and transportation. Sizes: 8" head diameter/53,3 cm height, 9 1/2", head diameter/58,4 cm height, 11 1/2" head diameter/62,2 cm height. Materials: Synthetic shell, Synthetic head. Features: Synthetic shell is perfect for outdoor playing - Non-slip rubber bottom - Lower tones with great resonance - Stackable for easy storage and transportation - Pre-tuned synthetic head for cutting sounds with sharp attack - includes three wodden beaters.