I have been using synthetic corks for wine that will be used soon, mostly whites, thinking if I give it away it will not be laid on its side, I have been using GEOS corks that masta has a link to above for my reds that will hopefully be aging for at least a year, however I just bought 900 natural corks also (the price was right). To help with the dimple with a two handed corked cut a 1/4" slice off a synthetic cork and put it on top of the cork you are inserting. (use it over and over)