Most LEGO keychain lights are made from ABS (Acrylonitrile Butadiene Styrene) plastic. At least one design (a banana keychain) uses a rubber construction.
They use LED lights, commonly placed in the feet or the bottom of the figure. Many models have an on/off switch located in the chest.
Most include a metal key ring designed for easy attachment to a backpack, purse, lanyard, or a set of keys.
Battery access varies by design. At least one review notes that the banana keychain’s rubber construction makes it easy to open for battery replacement, and some listings mention user-accessible, replaceable batteries—but ease of access depends on the specific model.
Most listings show a suggested age of 6 years and up and include CPSC choking-hazard warnings for small parts.
Many listings describe posable figures with movable heads, arms, hands, and legs. At least one listing notes a model with no articulation.