The 2008 ROAR rules originally permitted saddle pack batteries with a maximum height of 32mm based on the batteries available at the time. The rule was change in late 2009 to a maximum of 25.1mm to make them consistent with the majority of battery packs available on the market. The batteries in excess of 25.1mm were grandfathered for a period of one year to allow drivers to use packs already purchased under the original rule. The one year period expired in late 2010, so batteries legal for ROAR competition for the 2011 season and beyond will need to be in compliance with the existing rule. The battery packs in question will be removed from the approved list.