Here is a link to the Case O-rings (below). $1.50 for a 25 pack....$0.06 each and you can pick black or red. One O-ring can save a guy an entire $4 bag of platics. Worth every penny! I have used these o-rings on quite a variety of senko baits and haven't run into a "size" problems yet. There are some big bulky plastics up at Gander...forget the name....and they don't fit into the wacky tool very well. They fit just enough to get the o-ring started on the bait and with a little effort a guy can get them on. Never had an o-ring cut this bait in half but they are a very solid baits too.
http://caseplastics.com/case/product_info.php?products_id=110&osCsid=28be8d48eefe0f7d960319386004c8b7
Brian
You can pre-rig as many as you want. I bet I still have o-rings on some of my Big Magic Stiks from last year....still in the bag. I don't pre-rig them but I will just toss them back in the bag at the end of the day or when I switch up colors.
Al.....I was thinking about this a bit more....I have had the o-ring pull off some of the senko baits when pan fish bite on. Not very many but it does happen. The ones I had trouble with are the 3X ones....Strike King I think...that they sell at WalMart? They are very stretchy and hold up well but also pull out of the o-rings easier. I don't think I have ever had a Magic Stik or the Black Magic (Gander) brand pull out of the o-ring though.
You don't have to limit this to senko type baits either. If you can fit the bait into your wacky tool then you can "wacky" rig it!