Featured Thingie for removing watch backs

I have multiple inexpensive watches needing batteries. I need a doodad to make it easier to remove the backs.

Any thoughts on whether one of these would work?

 

the yellow one would work...
large grip area for control...

don't like the red one......looks like it's for bleeding an 18th cent soldier...

 

That's what I was thinking. I generally use one of my late dad's mini screwdrivers. He had them around for model work, but some of the little ones pry up watch backs just fine.

 

I'd use either but my usual case knife was like the second example. The ideal technique, if possible is insert and slide sideways rather than trying to lever it open, it's gentler and can often be done with a fingernail that would break if you tried direct leverage.
You are using the mechanical advantage of the wedge to reduce applied force.

 

Many thanks chaps. I'd not thought of needing one for screw backs, not even sure any of my watches have them, but given the widgets are cheap as heck on Ebay, I'll get both types. Much obliged.