Dualshock 4 Back Button Attachment in stock to purchase directly from PlayStation. Free Express Shipping for PS Plus members. $29.99
https://direct.playstation.com/en-us/accessories/accessory/dualshock4-back-button-attachment.3004784?emcid=bl-na-ds4bb2020-psd
https://direct.playstation.com/en-us/accessories/accessory/dualshock4-back-button-attachment.3004784?emcid=bl-na-ds4bb2020-psd