Stick-on bifocals - anyone tried them?

[Davidc]

I've been thinking about getting some of these to put on my sports glasses, to use when cycling.

If anyone's tried them I'd be very interested in how well you liked them.

 

[youngoldbloke]

Can't work out what these are - other than reading lenses. Allow your non prescription sunglasses to also be reading glasses? Not full prescription bifocals are they?

 

[Davidc]

@youngoldbloke my idea is to add these so with my normal distance vision contact lenses I can see maps, computer, etc.