Another slide rule which was so oxidised when i got it, i had to take sandpaper to it to free the slide. Anyway, this seems to be an earlier version of the 1010, probably (though i'm just guessing) from about the same vintage as the Model 4. It's a nice little trig rule which came in a cute felt case and belonged to someone named 'RUD'. They scratched their name into the back. Hiya, RUD. Nice slide rule, RUD.