Rule 4.3 applies to all types of equipment that a player might use during a round, except that the requirement to play with conforming clubs and balls is covered by Rules 4.1 and 4.2, not by this Rule.
This Rule only concerns how equipment is used. It does not limit the equipment that a player may have with him or her during a round.
4.3a. Allowed and Prohibited Uses of Equipment
A player may use equipment to help his or her play during a round, except that a player must not create a potential advantage by:
Using equipment (other than a club or a ball) that artificially eliminates or reduces the need for a skill or judgment that is essential to the challenge of the game, or
Using equipment (including a club or a ball) in an abnormal way in making a stroke. “Abnormal way” means a way that is fundamentally different than its intended use and is not normally recognized as part of playing the game.
This Rule does not affect the application of any other Rule that limits actions a player is allowed to take with a club, ball, device or other equipment (such as setting down a club or other object to help the player in lining up, see Rule 10.2b(3)).