There are four sheets to each voucher, which had to be filled out with a ballpoint pen. Since you were making four copies, you had to press down hard as you filled them out. The fourth copy was for the "supplier" or freelancer.
I have no idea if these are worth anything or not. I suppose I could go on eBay and see if anyone has or is selling them. I plan to hold on them for a while, so that's not an issue at present. When and if I do sell them, they will turn up in one of my online Vast Accumulation of Stuff sales.
Look for more mini-blog bonus posts as my time permits.