SCIENTIFIC DESIGN：CERROPI newton's cradle adopt scientific design,keep the pendulum balls perfectly lined up,make it possible to swing 50s+. Perfect demonstration of the scientific law of momentum conservation and energy conservation | SUPERIOR QUALITY：Our newtons cradle made of 8mm chromed metal steel bar, 20mm steel Ball,high-impact nylon, ultra-thin nano technology provide extremely durable oscillatory support, durable for long time use. | WIDE APPLICATION：This newton balls can be used as office desk gadgets toys to relieve stress; as teaching aid,teaching science intuitively; as toys for family activities, to inspire your child's creativity | EXQUISITE PACKEGING：We use individual wrapping paper to protect each ball and secure it in foam shockproof material,Perfect for Christmas gifts, Thanksgiving gifts, birthday gifts,Mother's Day gift,Father's Day gift,Valentine's Day gift etc. | WARRANTY & NOTICE：1 YEAR warranty, If any piece breaks we send replacement balls, strings and plug to you. Messages reply within 12 hours. NOTE: clean the ball thoroughly before using for the longer swing time,one extra ball and a silky soft cleaning cloth are included in the package