Unlike some manufacturers i could mention, Pickett didn't waste the back of this simplex trig rule. It's got nifty cheat sheets on how to use a slide rule. I guess this rule was probably designed to be used as a trainer for people just starting out with slide rules. I'm kinda regretting that i didn't find this before i gave my dad a Log-Log Duplex Decitrig for christmas (shut up, i know it's a weird gift).