Sealed Lead Acid are resistant to vibration, shock, chemicals, and heat this makes it very versatile.  The Sealed Lead Acid technology has a low self discharge, which means it hold a charge longer than other rechargeable chemistries such as ni-cd or nimh.   The electrolyte is suspended in a fiberglass mat separators which acts like absorbent sponges.  Sealed AGM batteries are of the chemical compounds lead dioxide, sponge-lead.  Shipping is not a problem with having a shipping class rating of 60 which is non hazardous and non sailable.   Comes in a wide range of sizes and voltages 2 volts to 12 volts and 1 amp to 200 amp. 

Replacements