First Quality Straight Wine Corks - 44 by 22mm / 8x1 3/4 - 30 per bag
Wine bottles have an industry standard neck opening (with very few exceptions in North America) and most corks are 1 3/4" in length. The 7, 8 or 9 indicates the diameter of the cork.
The larger the number the snugger the fit will be, and less air will enter your bottle. Small amounts of air do help your wine age, however with smaller corks more air is allowed to enter your bottle which will shorten the storage time.