Purpose of Rule: Rule 4 covers the equipment that players may use during a round. Based on the principle that golf is a challenging game in which success should depend on the player’s judgment, skills and abilities, the player:
Must use conforming clubs and balls,
Is limited to no more than 14 clubs and
Is restricted in the use of other equipment that gives artificial help to their play.
(1) Conforming Clubs. In making a stroke, a player must use a club that conforms to the requirements in the Equipment Rules when:
It is new, or
Its playing characteristics have been changed in any way (but see Rule 4.1a(2) when a club is damaged during the round).
But if the playing characteristics of a conforming club change because of wear through normal use, it is still a conforming club.
The “playing characteristics” of a club are any part, feature, or property that affects how the club performs or aids in alignment, including but not limited to, weighting, lie, loft, alignment features and permissible external attachments.
(2) Use, Repair or Replacement of Club Damaged During Round. If a conforming club is damaged during a round or while play is stopped under Rule 5.7a, except in cases of abuse, the player may repair it or replace it with another club.
But no matter what the nature or cause of the damage, the damaged club is treated as conforming for the rest of the round (but not during a play-off in stroke play, which is a new round).
For the rest of the round, the player may:
Continue to make strokes with the damaged club, or
Except in cases of abuse, repair the club or replace it with another club (see Rule 4.1b(4)).
If the player replaces the damaged club with another club, the player must take the damaged club out of play before making another stroke using the procedure in Rule 4.1c(1).
“Damaged during a round” means when any part, feature, or property of a club is changed because of any act during the round (including while play is stopped under Rule 5.7a), whether:
By the player (such as making a stroke or practice swing with the club, putting it in or taking it out of a golf bag, dropping or leaning on it, or throwing or abusing it), or
By any other person, outside influence or natural forces.
But a club is not “damaged during a round” if its playing characteristics are deliberately changed by the player during the round, as covered by Rule 4.1a(3).
(3) Deliberately Changing Club’s Playing Characteristics During Round. A player must not make a stroke with a club when they have deliberately changed that club's characteristics during the round (including while play is stopped under Rule 5.7a):
By using an adjustable feature or physically changing the club (except when allowed to repair damage under Rule 4.1a(2)), or
By applying any substance to the clubhead (other than in cleaning it) to affect how it performs in making a stroke.
Exception – Adjustable Club Restored to Original Position or Non-Permissible External Attachment Removed: There is no penalty and the club may be used to make a stroke in the following two situations:
If a club’s playing characteristics were changed by using an adjustable feature and, before the club is used to make a stroke, the club is restored as nearly as possible to its original position by adjusting the feature back to where it was.
A non-permissible external attachment (such as a sticker on the club face) is removed from the club before the club is used to make a stroke.