In addition, Mark is an inventor, published author and consultant. He invented pivoting glide bars for the EKTELON Model H and NEOS 1000 stringing machines, a device that aids in the correct stringing of fan-pattern racquets on these particular stringing machines.

Mark is a current member of the Babolat VS Stringing Team which is the official stringer of the French Open. Previously, he was a member of the Bow Brand Stringing Team which was the official stringer of the Wimbledon Championships. Mark has strung for many Grand Slam winners including Patrick Rafter, Mary Pierce, Carlos Moya, Andy Roddick and Roger Federer.

Fluent in three languages, Mark has a bachelor's degree in foreign languages and literature from the University of Wisconsin in Madison and a master's degree in marketing communications from DePaul University in Chicago.

Mark began teaching tennis in the '80s as a complement to his racquet stringing business, and to help supplement his income while attending graduate school.

"I love tennis, being my own boss, sharing my tennis knowledge and being an expert in the field of racquet stringing & customization," Mark says.

He has also spoken at the USPTA Midwest Division Convention in 1991, '97, '99, 2003 and 2005.