The device consists of an integrated circuit connected to a series of exposed electrical contacts, in a curved package which matches the lens mount.
It is designed to be affixed in a particular position on the mount, in order to mate with matching contacts on the camera body.
Camera functions enabled by the chip may include exposure metering, aperture display and control, focus confirmation and fine-tuning, and Exif metadata recording.
The level of additional functionality enabled by the chip depends on the camera.
By contrast, many consumer-level Nikon DSLRs require an electronically enabled lens to perform functions as basic as metering.