Minor League Baseball will implement a series of rule changes designed to reduce the length of games for the 2018 season, the organization announced Wednesday. The moves come as part of an ongoing experiment in baseball to shorten games, particularly those that go into extra innings.

The procedures, which MiLB says were made in partnership with MLB, “aim to reduce the number of pitchers used in extra innings and the issues created by extra innings games,” which include position players being used as pitchers and shortages of pitchers in the days following unusually long games.

The announcement says that a 15-day grace period will go into effect from April 5-19 where players will receive warnings. Starting on April 20, the new rules will be fully enforced as written. Here’s a rundown of the most notable changes.

Extra innings start with runners on second

At all levels of the minors, extra innings will now start with a runner on second base. The runner will be the player who is in the batting order position previous to the leadoff hitter for that inning. So if the No. 4 hitter is due to lead off, then the No. 3 hitter goes to second base to start the inning. This is a rule being adopted from softball, and it’s likely to be the most controversial.

Limited mound visits

Mound visits are also being addressed as part of the rule changes. A mound visit is defined as anytime a manager, coach, or teammate meets the pitcher at the mound with only a few limited exceptions (such as following an injury or to clean spikes in rainy conditions).

The amount of mound visits each team will be allowed depends on the level. At the Triple-A level, it will be just six per game, while at the Double-A level, it will be eight per game. At Single-A, it bumps to 10 per game, and there will be no limit for teams in short season or rookie leagues. For extra innings, each team will receive an extra mound visit for each inning played.

15-second pitch clocks

At the Double-A and Triple-A levels, a 15-second pitch clock is being implemented when there are no runners on base. If a pitcher fails to begin his windup or “motion to come to the set position” within 15 seconds then a ball will be added to the count. If a batter is not “in the batter’s box and alert to the pitcher” with seven seconds left on the clock, a strike is added to the count. The minors have used 20-second pitch clocks in the past, and now they’re experimenting with an even shorter time frame.

MLB declined to implement a pitch clock at baseball’s highest level for 2018, but the experimenting in the minors could lead to changes at that level eventually.