These are 5mm UV LDs in a shorter 375nm wavelength. Most UV LDs are around 400nm and are dirt cheap, but the shorter the wavelength, the higher the cost due to the greater manufacturing expense.
These are new high grade Nichia LDs in a metal can with glass window and narrow viewing angle. Part number NSHU591A, radiant flux rank 6 (4.72 to 6.66mW @ 20mA).
Note that most of the emission is at 375nm so these don't appear bright to the human eye.
