This is Kenner's Six Million Dollar Man Critical Assignment Arms set from 1976. That title's a mouthful...but deservedly so. The SMDM toys were some of the best toys ever created. This set again demonstrates the great playability that Kenner injected into this line.
The set came with three different bionic arms to equip your Bionic Man (sold separately) with new bionic features. Each arm popped on and off easily and had a roll of rubber skin to cover the bionics to keep Steve's bionic-ness covert. It also came with a white short-sleeved t-shirt (complete with SMDM logo on the chest) to provide easy access to Steve's new arms.
The set features a "Laser" arm that lights up when Steve's hand is bent back at the wrist, a Neutralizer Arm with spring-loaded karate chop and neutralizer gun behind a door in the bicep, and the Oxygen Supply arm with oxygen mask.
A more thorough explanation of each arm's features can be seen in the instructions below.
I had this set as a kid but managed to lose every arm over time despite still having my original Steve Austin figure. I love the concept of this set and the opportunity it provided kids to add brand-new play features to a toy they already owned...vs. selling a whole new figure with new arm features (although Kenner did that from time to time, as well).
Am I just getting old or do they not make toys like they used to? I'm probably just not paying as much attention to newer licenses and toys.