If you are not 100% sure of which generation controller you have, we highly recommend you open your controller first to check the motherboard model before you purchase.
The L1 R1 buttons are only fit for the second-generation PS4 controller. (Motherboard Model: JDM-040, JDM-055)
There is a tip here might be helpful in case you don't have the tools: The second-generation controllers come with a very thin light bar on top of the touchpad and most of the first generation controllers don't.

INSTALLATION GUIDES:
Designed for PS4 controllers only.
Requires technical internal fitting, the modded PS4 controllers must be opened to install.
The tool required to replace the buttons is included in the package.
Watch installation video on Youtube will be helpful if you do not know how to install them, be careful and patience will avoid some unnecessary mistakes.

PACKAGE INCLUDES:
1 x Metal L1 L2 Buttons
1 x Metal R1 R2 Buttons
2 x Springs

Notes:
The PS4 controller is not included.
Each item has been well tested before delivery, but we cannot 100% guarantee it won't be defective because of transportation. Any problem, please feel free to contact us through Amazon Email System and we will do our best to solve it.