The SDP8406 series, from Honeywell, is a family of silicon phototransistors. They are in side-looking (SL) packages with a rectangular package. The chip is positioned in a lens on the side of the package to enable it to accept radiation from the side.
Features of the SDP8406 phototransistors:
Side looking (SL)
Rectangular package
Through-hole mounting
Acceptance angle: 50°
Wide sensitivity ranges
Operating temperature: -40 to +85 °C