It's an HL-DT-ST (LG) rebadge. Of which model, I don't know and couldn't tell you if I tried to guess, especially given that it's a slim drive.
For some reason, when HP rebadges LG's drives, they mangle the ID string even worse than when LG gives drives to other OEMs. If you will, take note that LG's typical full names are something along the lines of GH24NS70 or BH10LS30, but it seems to be content to give OEMs something like GT50N with no chance of finding a compatible retail firmware or OEM firmware. Of course, someone with more knowledge than me could probably point you in a better direction if you needed more info.