Prototype clubs

If you look on Titleist's web site, it is listed that Ernie Els is using a prototype Titleist driver and 3-wood... Also his Pro-V1's are listed as prototype balls.

See: http://www.titleist.com.fr/5507_9731.htm#

I wonder why he is allowed to use a prototype club/ball on the tour...

Shouldn't this be illegal? By definition, if the club/ball is a prototype, it's because it is still in development, therefore it must not have been approved by the USGA or R&A, correct?

Gary can you please explain this situation?

I think the use of the word "prototype" in this instance means it is not yet commercially available to the public but that it has gone through testing. I know when Tiger Woods started using the Nike ball it was not available to the public until some time later.

Exactly.