Good news! The PS4 controller's Back Button Attachment works on iOS. | iMore
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)
DualShock 4 Back Button Attachment review: small but perfectly formed | Eurogamer.net
Gamepad Back Button Attachment with 3.5mm Audio Interface for Sony PlayStation 4 PS4 DualShock 4 Wireless Controller Accessories|Replacement Parts & Accessories| - AliExpress
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)
Amazon.com: DualShock 4 Back Button Attachment - PlayStation 4 : Video Games
Sony PS4 DUALSHOCK®4 Back Button Attachment
PlayStation 4 DualShock finally has cost-friendly back buttons: Review | Mashable
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)
DualShock 4 Back Button Attachment review | TechRadar
DUALSHOCK 4 Back Button Attachment - FULL REVIEW & SETUP GUIDE | A Perfect Upgrade! - YouTube
DualShock 4 Back Button Attachment Review - IGN
Amazon.com: Sony DualShock 4 Back Button Attachment : Video Games
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)