SHRED FLEXI BACK PROTECTOR VEST ZIP Spine protector: The Shred FLEXI BACK PROTECTOR VEST ZIP. The patented shock-absorbing material adapts intelligently and progressively to different forces and impact speeds for thorough protection - even during low-energy impacts. Simply put, it stays flexible while you are riding, but hardens to protect you when you fall. SHRED FLEXI BACK PROTECTOR VEST ZIP