How To Downgrade Your 4.90 CFW PS3 *Easy* - YouTube
Liste PS3 compatibles Downgrade Jailbreak | Console X
How to Downgrade CFW on a Jailbroken PS3 - YouTube
PS3 Downgrader 3.55 - Consoleinfo
DownGrade/Jailbreak Service
Downgrading with PSgrade Dongle - PS3 Developer wiki
PS3 Downgrade Jailbreak USB Key(id:4997490) Product details - View PS3 Downgrade Jailbreak USB Key from China Shengmeng Electronics Co.,Ltd - EC21 Mobile
Downgradable PS3 Models & Base Firmware with MinVerChk | PSXHAX - PSXHACKS