Marathon has been selling tubular lead-selenium vented batteries for nearly 4 years. The combination of the tubular Selenium cell combines the advantages of both lead calcium and lead antimony cells while exhibiting none of the disadvantages. Due to increased positive plate surface area, tubular plates have more electrical capacity than flat plates of comparable size and weight. With positive plate shedding eliminated, tubular batteries also provide up to a 30% longer service life than flat plate batteries. Perhaps most importantly to stationary applications the tubular positive grid does not require horizontal bars, which virtually eliminates positive plate growth and therefore post seal leaks and jar cracking. As a result, in applications which require a long service life, tubular plate batteries provide the best and most reliable power.