Amazon.com: DualShock 4 Back Button Attachment - PlayStation 4 : Video Games
Paddles For Ps4 Controller, X-Gun Back Button Attachment For Playstation 4, Controller Paddles For Ps4, Turbo Function/Memory Function/Plug And Play, Suitable For Ps4 Handles - Walmart.com
Trade In Sony DUALSHOCK 4 Back Button Attachment | GameStop
Introducing the DualShock 4 Back Button Attachment – PlayStation.Blog
DUALSHOCK 4 Back Button Attachment | Hardware and Accessories | PlayStation (US)
Strike Pack for PS4 Controller, Controller Back Button Attachment,Paddles for PS4 - Walmart.com
Sony's Back Button Attachment is finally back in stock, so here's our review | Ars Technica