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What Is a High-Rebound Driver? How to Spot One and Where You Can Use ItThe limit is CT 239 microseconds. I set the numbers for the PRGR SUPER egg, which exceeds it, next to the PING G440 K.

Updated: Oct 26, 2026Contains affiliate links

I average a score of 72 and play 150 rounds a year. I compared these seriously.
A high-rebound driver is a "non-conforming" club that goes past the rebound limit. The limit is CT 239 microseconds (tolerance 18).
The PRGR SUPER egg driver is ¥151,800, and PRGR itself says it is for private play only.

Header image product photo: Rakuten Ichiba (ad) | PRGR SUPER egg driver

Bottom line

What Is a High-Rebound Driver? The Rules Limit Is CT 239 Microseconds

The Rules of Golf limit how much a driver face can act "like a trampoline" and fling the ball. This is the spring-effect rule, which Japan calls the SLE rule.

It's measured with the characteristic time (CT): how long the ball and the face stay in contact, in microseconds (millionths of a second). The more the face flexes, the longer the contact, and the bigger the number.

The limit is 239 microseconds. The test allows a tolerance of 18 microseconds, so a reading up to 257 is still ruled conforming (239 + 18 = 257, my calculation).

The rule has applied to elite golf since Jan 1, 2003, and to every player at every level since Jan 1, 2008 (the Japanese version of an R&A document published by the JGA, dated Mar 13, 2008). A club past the limit is what people generally call a "high-rebound" club.

PRGR SUPER egg Driver Numbers

The best-known high-rebound driver still sold in Japan is PRGR's SUPER egg. Here are the numbers from the official product page.

Source: PRGR's official SUPER egg driver product page (checked Oct 26, 2026). The page gives no length for the M-35, and no CT figure is published.

The product page gives three usage warnings. First, "use only for private play." Second, "do not hit it if your head speed is 43 m/s or more." Third, the head volume and head shape are also non-conforming.

On rebound, the page says "the highest rebound performance in SUPER egg history" and "thin-wall area around the face expanded to 130% of the previous model." It gives no figure for how many yards you gain.

How Does It Differ From a Conforming Driver? Set Against the PING G440 K

As a stand-in for a regular current model with no high-rebound label, I set it next to the PING G440 K, whose official numbers I've already read on this site.

Source: PRGR's official product page and PING's official product page (numbers checked for this site's PING G440 K article). The rule label is what PRGR's product page states.

Doing the math, the SUPER egg is 21–25 g lighter than the G440 K (301−280, 301−276) and 0.5–1 inch shorter. It costs ¥33,000 more (151,800−118,800, my calculation).

I read the lighter, shorter build as a way to let slower swingers finish the swing with a head that has more rebound. It also fits the product page's warning not to hit it at a head speed of 43 m/s or more.

Where Can You Use a High-Rebound Driver, and Where Not?

PRGR's official answer is "private play only."

The rebound rule applies to golfers of every level (JGA document). How it's applied in a given competition is up to the organizer, though. PRGR's SLE page says the same: even clubs within their conforming period may or may not be covered, depending on the event, so ask the organizer.

So here's where I'd draw the line. A normal round alone or with friends you know well: fine. Monthly medals, club championships, company or friends' tournaments: ask the organizer first. If you're unsure after asking, leave it at home.

Three Things to Check Before You Buy

First, the product name. On Rakuten, many listings put "[high-rebound model] [non-conforming]" or "non-conforming to the SLE rule" right in the title (checked Oct 26, 2026 in Rakuten's product search). A club with those words is a non-conforming club.

Second, your head speed. PRGR doesn't recommend the SUPER egg for players at 43 m/s or more. Use your usual driver number as the guide (a range or shop launch monitor will tell you).

Third, where you expect to play it. Will you play in a competition or group tournament in the next year? If so, you'll need a conforming driver on top of the high-rebound one. Work out what owning two will cost before you buy.

If you also play competitions, I'd treat a high-rebound driver as a second club. Your first should be a conforming club you can use anywhere.

Who is it for?

Great for you if you

• You skip competitions and mostly play private rounds
• Your head speed is under 43 m/s
• You want a light, short driver that's easy to swing through

If there's even a small chance you'll play in competitions, start with a conforming driver for beginners.

SUPER egg Driver Price and Where to Buy

The official list price is ¥151,800 incl. tax. At 150 rounds a year, 1 year of use works out to about ¥1,012 per round (151,800 ÷ 150; the figure is per 1 round, my calculation).

When you buy, make sure it's a Japan-market official model and that the shaft suits your head speed. The shaft is dedicated, in three types: M-40, M-37 and M-35.

For a comparison of the latest models, see New Drivers 2026. For a conforming driver compared on forgiveness, see the PING G440 K review.

Where will you play your next driver?

Update history

• Oct 26, 2026: Published (based on the R&A document published by the JGA, and PRGR's official product page and SLE page)

About the writer and sources

Written by a gear nerd who studies golf equipment, averages a 72, and plays about 150 rounds a year.

I re-read the numbers against the sources below on Oct 26, 2026. Last updated Oct 26, 2026.

FAQ

Related reading

Best Drivers for Beginners
An article on choosing a conforming club rather than a high-rebound one.

PING G440 K Review
The conforming club I set against it in this article.

Latest Drivers 2026
The 2026 new releases, lined up by loft and price.

Sources for this article

• JGA: Check Test for Driving Clubs (Japanese version of an R&A document, Mar 13, 2008)
• PRGR official: SUPER egg driver / high-rebound model
• PRGR official: About the SLE rule

Last updated: Oct 26, 2026

Specs and prices are the figures published on manufacturers' official websites and in press releases, and by media outlets (checked Oct 26, 2026). They were not measured by this site.