The 28l is a model of 6-volt battery under the Duracell brand that is not equivalent with the SUM5 style of 1.5-volt batteries that are sold under several brands. The batteries are also different lengths and only fit in the type of equipment for which they were designed.
Duracell's 28l is a lithium battery designed specifically for the power requirements of digital cameras. The batteries provide long-lasting power at 165-milliamperes. The SUM5 is a standard N-size dry cell battery designed for electronics with much lower power requirements, such as small flashlights, remote controls, wireless microphones, clocks and laser pointers. SUM5 batteries typically incorporate suffixes that describe the types of dry cell batteries, including R1 for zinc-carbon, LR1 for Alkaline, KR1 for nickel-cadmium and HR1 denoting nickel-metal hydride.