Loft is extremely important in a gap wedge but knowing the bounce of the club and if you are comfortable with it is also vital to shooting low scores.
The bounce is the rounded curved part of the head of the wedge. The bounce is created to help players from getting their club stuck in the ground when swinging. If the club digs in a bad shot will more than likely be the result.
If you place a wedge flat on the ground the leading edge will be barely off the floor. The higher that the edge is from the floor the higher the bounce will be on the club.
If the bounce of a club is 0-10 degrees then it will be easier to hit off tighter lies and firmer, harder grounds.
If you play on wet courses or during a rainy day the wedges with bounces of 10-16 degrees will be easier to hit and will have a lesser chance of getting stuck in the ground during a swing.
It’s ultimately up to the golfers’ swing style to decide on what kind of bounce they prefer playing with their wedges.