3.1v charger bundle, charge time?

I'm no electrical engineer:

I was going to buy, what appears to be a good deal, a bundled charger-lightning cabe-wall/car deal that has a 3.1v (3 devices charging at once via car charger) and was wondering if the 3.1v makes the charging process slower???

Looked on &amazon and couldn't find a better deal, but is it worth a potential slower charging rate?

Thanks...

tcb