Sodastream easy open cap cover

I like "sodastream" bottles and use them while cycling. 

But when my hands are wet, unscrewing the original caps is very difficult. 

These covers for the original caps do the trick. 

They add little to their size (they are quite thin, look at third photo about size comparision), but unscrewing the bottles is no longer a problem. 

Insert the original cap into this cover.  

They look better printed than in photos, have fun using it.