Simplify the following text for a Grade 12 native English-speaking person.
Original: The band also includes guitarist David Kennedy , notably from Over My Dead Body , Hazen Street and Box Car Racer , drummer Atom Willard from The Offspring and Rocket from the Crypt , and bassist Matt Wachter from 30 Seconds to Mars , who replaced Ryan Sinn in 2007 .
Simplified: The memers of the band were Atom Willard , former Offspring drummer ; Matt Wachter , former bassist of 30 Seconds to Mars ; and David Kennedy , former guitarist of Hazen Street and Boxcar Racer .