The spare Air Ram battery enables you to complement your current vacuuming power, doubling the amount of vacuuming time your Graphite Gtech Air Ram delivers to more than an hour. It's handy to have around if you have a big home, or to use around the office. With the Gtech Air Ram spare battery you get the convenience of having an additional vacuum battery, fully charged & ready for you to plug in & use. It gives you up to 40 minutes extra vacuuming time plus the peace of mind of having a fully charged spare in reserve.