The 4 reels slots are just a step ahead from the old school 3 reels. They offer the players huge winning chances. The free 4 reel online slots mostly feature up to 20 pay lines, offering a large number of combinations to win. The more is the reels, the more will be the paylines. Most 4 reels slot games are rewarding as they come with bonus rounds and some symbols. A few of them are even integrated with progressive jackpots.