These Nichia LEDs measure around 3.2 x 3mm. I have been unable to find any specs on them but they are a typical top emitting wide angle LED, and being Nichias, they will be bright.
Part number is NECG310T-Y2 and they are R brightness rank. Manufacture date 2007.
Note: photo is indicative only.
I am looking to clear these out quickly, so make me an offer for the roll, you might get a real bargain!