One of the biggest discussions in golf these days is the subject of conforming and non-conforming drivers. Callaway Golf knows that different golfers have different reasons for playing the game. Whether you seek to lower your score, add more distance to your drives, or just have fun with family and friends, our goal is to help you find more enjoyment – whatever game you play. That’s why we give you a choice when it comes to our drivers.

Currently, each of our Callaway Golf drivers is offered with a Standard (warm) version, as well as a Plus or + (hot) version, which has higher clubface efficiency and offers more potential distance. In general, the Standard version driver conforms to USGA Rules of Golf, while the Plus version driver currently conforms to R&A Rules of Golf now in effect.

Here’s our fact guide to help you make an informed decision based on your style of play and the rules that govern play around the world. We also recommend that you visit the R&A’s website at http://www.randa.org to learn more about conformance testing and rules. Enjoy the game.

What is Characteristic Time, or CT?

Characteristic Time (CT) is a measure of impact efficiency, sometimes called the “spring-like effect” in drivers. CT has recently replaced what used to be measured as Coefficient of Restitution, or COR. CT is a measure of the responses of a driver face to an object impacting it – in short a measure of the efficiency of impact. Higher CT impact efficiency equals more efficient energy transfer from clubface to ball, and that means more potential distance.

How Does CT Testing Work?

CT driver testing conducted by the Royal and Ancient Golf Club of St. Andrews and the United States Golf Association consists of a steel weight suspended from a pendulum, which is then released from varying heights to strike the clubface. The amount of time that the weight and clubface are in contact determines a driver’s CT; the limit has been set at 239 microseconds, plus a test tolerance of 18 microseconds, for a maximum of 257 microseconds. This testing was jointly developed and approved by the R&A and the USGA.

Which Clubs Will Be Tested?

If you play in Europe, or anywhere that the rules of the R&A apply, there is currently no limit on CT. For amateur players, a Plus or + (hot) version driver is acceptable for play and handicap purposes until January 1, 2008.

For elite players in Europe, the R&A will limit CT at all championships and international matches beginning in 2005. For most competitions and all recreational play, there will continue to be no limit on “spring like” effect until 1st January 2008. However, the decision to extend the application of the Conditions to top Amateur events begins on 1st January 2005.

We strongly recommend that you contact your respective golf union to confirm any equipment restrictions for Amateurs events:

English Golf Union:    Tel +44 (0) 1526 354500 or www.englishgolfunion.org
English Ladies Golf Association:   Tel +44 (0) 121 4562088 
Golfing Union of Ireland:  Tel +353 1 2694111 or www.gui.ie
Irish Ladies Golf Union:  Tel +353 1 269 6244
Scottish golf Union:  Tel +44 (0) 1382 549500 or www.scottishgolf.com
Scottish Ladies Golfing Association:  Tel +44 (0) 1382 549502
Welsh Golfing Union: Tel: +44 (0) 1633 430830 or www.welshgolf.org
Welsh Ladies Golf Union: Tel: +44 (0) 1633 422911

In the United States and where USGA Rules apply, the CT limit has been set at 239 microseconds, plus a test tolerance of 18 microseconds (257 maximum) for professionals and amateurs who maintain an established handicap. All Standard (warm) version Callaway Golf drivers conform to USGA Rules regarding CT.

CT testing applies to drivers only; fairway woods are not subject to the pendulum test or CT restrictions.

Where Does CT Testing Apply?

The R&A and the USGA jointly developed, approved and adopted the new CT pendulum testing device for driving clubs; it went into effect in January 2004. The R&A is the governing body for golf everywhere outside the United States and Mexico; the USGA is the governing body for golf in the U.S. and Mexico. The Royal Canadian Golf Association establishes the rules of golf in Canada and has adopted USGA limits in regard to CT for amateur and professional players. 

The R&A will apply the pendulum test and CT limits in 2004 at The Open only. Beginning in 2005, the R&A will begin testing all drivers at all of its championships and international matches. For all recreational players, amateurs and most competitions in R&A territories, there will be no limit on CT until January 1, 2008. At that time, a limit of 239 microseconds (plus a test tolerance of 18 microseconds for a maximum of 257 microseconds) will go into effect for all driving clubs.

The USGA currently considers any driving club that exceeds the 239 microseconds (plus a test tolerance of 18 microseconds for a maximum of 257 microseconds) to be non-conforming for amateur and elite players and for handicap purposes.

Standard Version Callaway Golf Driver (conforms under USGA and R&A Rules)

The face thickness of a standard Callaway Golf driver (warm) produces a CT (and formerly a COR) that conforms to the current R&A condition of competition for elite players and USGA rules. A standard Callaway Golf driver can be played anywhere in the world, by amateurs and professionals, for competition and handicap purposes.  

Plus or + Version Callaway Golf Driver (conforms under R&A Rules until January 1, 2008)

The face thickness of a Plus or + version Callaway Golf driver (hot) delivers ultra-high CT (and formerly a COR) technology for even greater potential distance.

A + version driver can be used by amateur golfers in R&A territories until January 1, 2008; the + version conforms to the R&A Rules for most competitions and recreational play until January 1, 2008. At that time, the R&A will begin to limit driver CT, and any driver with a CT that exceeds 239 microseconds (plus a test tolerance of 18 microseconds for a maximum of 257 microseconds) will be considered non-conforming for handicap and competition purposes for both amateur and elite players.

The + version driver exceeds the current USGA CT limit and does not conform to USGA Rules.

The + version of a Callaway Golf Driver is clearly marked with a + symbol on the sole of the club.