Sidearm Distance (Frisbee) 

Sidearm Frisbee, a Frisbee throwing technique, placing the disc between the thumb and first two fingers then throwing from the side. (similar to a sidearm baseball throw)

Ken Westerfield's sidearm distance record of 552 feet, with a 119 gram World Class Model Frisbee, Boulder Colorado 1978, and Victor Malafronte's, 538 feet also with a 119 gram Frisbee, not only have the longest sidearm throws of all time but are the best sidearm throwers of all time.

At a North American Series (NAS) Frisbee tournament in Dallas Texas, Westerfield became a member of the "400 club" with a prelim distance sidearm throw, and won the event with a throw of 378 feet, using a 119-gram World Class Model Frisbee. Only two competitors have officially ever thrown over 400 feet in competition with a 119-gram Frisbee (Lightweight disc by today's standard).

1978, in Boulder, Colorado, while doing a distance throwing demonstration at a North American Series (NAS) Event, Westerfield threw a sidearm 119-gram World Class Model Frisbee, 552 feet, shattering the official world distance record of 412 feet

Tournament officials marked and measured the throw at 552 feet. Since the introduction of heavy weight, sharp edge disc, the world record is now over 800 feet. However Westerfield's 552 feet is still the record for the sidearm throw

Sidearm Distance (Frisbee) is covered in several Wikipedia Articles

Sidearm Distance (Frisbee) by Disc Sports August 1, 2012