Deep Cycle : Premium sealed batteries capable of up to 1000 cycles (50% DOD) as fully tested by independent laboratories. Gelled/Suspended Electrolyte : No liquid of any kind; battery is completely sealed. Safe in any position (except upside down). Maintenance Free: Water is never added; low liability Do not need to be fully discharged before recharging. Do not develop a "memory" that limits their recharging. Travel & Ship Easily : MK batteries are F.A.A, IATA, and UPS approved. Others may not be.