These little LEDs are made by Stanley Electric Co Ltd. They are part number BR3365S.
They are a cylindrical V-cut LED with a tinted lense and flanged case.
Peak wavelength is 647nm, making them a deep red colour. Luminous intensity is 5mcd @ 20mA. Forward voltage drop is 2 volts max.
They measure 4.1mm high x 3mm diameter. They have lead stand-offs at 6mm.
They are primarily designed as side-emitting LEDs, but when viewed straight on, they appear as a point source. They are ideal as low cost indicators for general projects, or for many other uses.
Datasheet is here.
This is a bag of 200 LEDs, so they are just half a cent each, amazing value for such high grade LEDs!