I use small ones on BOTH tips of the bow. I make them out of small diameter ? rubber hose, and make them short so they don't contact the string when the bow is drawn. I put a slight curve on the outer edge and use super glue to hold the end closed then install them on the bow. They are cheap and easy to make and I always carry a couple spares in my quiver, pack etc. I have found that the upper limb tip can get banged up just as easily as the bottom, so I use two. Just my thoughts,....Lloyd  

Never had a problem with them.  Depending on your bow, some are too long and will cover part of the string over string groove...mostly on longbows.  Just trim them back so the only cover the tip no problem.

I don't use them. I'm afraid of the moisture thing damaging the finish/wood tip.

Here's another good tip protector that is cheap. Soft Plastic Screw protectors.  You can find them at any hardware store. I got a bag of three of them for 50 cents an Lowes.  I have a Whip and the 3/8 size fits the bottom limb tip perfect. Fits snug but is easily removed and does not interfere with the string and stays put when you shoot.  Best of all, they are CHEAP!  Check it out.

Thanks for the soft plastic screw protector idea.

That's a great idea!    

I'm sure they serve a purpose, but I have never used one....I also do not use my bow as a walking stick like Fred Bear did crossing rivers in some of his videos.  Now my wife's bow is a different story. I put one on her bow and it does not seem to affect her arrow flight or performance.