CLEMSON - Sammy Watkins is now officially a very rich man, between his endorsement deal with adidas and Wednesday's signing of his four-year contract to thrive in the Buffalo Bills offense.

Watkins has secured a four-year deal worth $19.9 million, including a $12.8 million signing bonus, all guaranteed. The former Clemson All-American put pen to paper shortly after his first organized team activity (OTA) practice in Buffalo.

"The best moment of my life right now," Watkins told BuffaloBills.com. "Just to know you have financial stability, and now every day I can come in and worry about football, my plays and my job. Just worry about the connection of the offense and learning from the older guys. That's what it's about."

The fourth pick in the 2014 Draft, Watkins' endorsement details with adidas are not being publicized, though a source said it is the largest apparel deal for a wide receiver since Calvin Johnson, the second pick in the 2007 Draft and a four-time Pro Bowler with the Lions.

Four of Clemson's five draft selections on May 8-10 have now signed contracts with their teams: Brandon Thomas has signed with the 49ers, Bashaud Breeland with the Redskins and Tajh Boyd with the Jets. Only Martavis Bryant, a Steelers wide receiver, is yet to firm up his pro contract.