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 NSCE310T and they are S brightness rank. Manufacture date 2006.
Note: These tend towards the green end of the cyan range, not blue! Photo is indicative only.
I am looking to clear these out quickly, so make me an offer for a roll, you might get a real bargain!