SentrySafe PL048E Electronic Security Box, 0.5 Cubic Feet, Black Best used to secure laptops, cell phones, and other valuables; Great holiday gift for college students, young adults, or children Set your own combination for keyless convenience; secure safe to a stationary object with the tethering cable Portable safe is constructed with solid steel for reliable protection Exterior: 17.5 in. W x 13.6 in. D x 5.8 in. H, Interior: 16.4 in. W x 11.3 in. D x 3.6 in. H; large capacity 0.5 cubic feet; weighs 15 pounds For optimal performance, SentrySafe recommends the use of four high-quality, name branded, alkaline AA batteries with an expiration date of 8-10 years from the current year. Generic and rechargeable batteries often do not have the lifespan needed to support long term usage