What's the round side of a bottle opener for ?

[Jokester]

Like this one -
Discount Wood Flat Beer Bottle Opener Vintage Wooden Handle Bar Kitchen Wine Beer Openers For Party Beer Opener Bar Supplies LX1908 Top Openers Online Shop | DHgate.Com

Or in metal - Bartender's Bottle Opener Hardware Kit | Rockler Woodworking and Hardware

They're showing a lot of work going into making it, but not how to use it LOL.
I have one made by newcastle with some sort of rubberized coating over the entire thing except the regular side which is bare metal.

So it can be metal, rubber or wood ? But what does it do ?
I use it to hang on a magnet by the side of the fridge collecting dust mainly cos I use the plastic "jar-key" to pry off, and if I ever had a twist off, well I use my hand or the round ones made in Canada called a "bev-key".

 

[matt_m]

According to the second link…

Though you can use the hole on the opposite end for hanging the bottle opener, it's actually expressly designed so you can spin it on your finger, a critical feature for the aspiring home bartender.

 

[DuncB]

I use the round end to pick the bottle top off the floor it fits just over the bent bottle top with enough friction and then I can push the bottle top out of the hole and into the bin.

 

[Jokester]

Oh, OK the rubberized coating prevents spinning by snagging, the serrated one I have can be spun but it might nick the skin, but the metal and wood if sanded smooth and lacquered would spin well, OK let me practice that every time I open a bottle. Then hang it back and use my jar-key. Oh wait, I dont have wood or metal.
Now, pick up the cap off the floor, well that's another idea there.

 

[balrog]

Now, pick up the cap off the floor, well that's another idea there.

embedded rare earth magnet