I have come across a variety of Interlake/Acme pen knives which were likely all given out as safety awards.
The first of course is the money clip/knife I got from Steve Buckner. It is a real beauty – you can see the details about that one at the link above.
I have since purchased two different knives on ebay for a low cost. This Interlake knife has such a snappy action that it is addicting. Even though the seller included a ruler in the photo below, I was shocked at how tiny this knife is, it is probably 1/2″ wide.
I had seen this one before but the price was prohibitive. However a good deal of time later, another came around. They wanted only $10 – I lowballed an offer at $5 and they came back at $7. Deal!