DUALSHOCK 4 Wireless Controller PS4 - Tested and Working - DualShock 4 Black Regarding Operation Confirmation: All buttons and sticks have been tested using a dedicated tool. Button responsiveness, which can be difficult to assess during actual gameplay, is evaluated numerically. If a button's response isn't 100%, it's excluded from being considered a normal product. Axis drift is also excluded if it's not at the correct center value. Stick operation is also checked for subtle drift that's not easily noticeable during gameplay.