Start button lacks its black conductive pad so it doesn't work.

Quality control problems.

Edit: Handheld Legend has already sent out a replacement after a quick and easy email! Think you'll be in good hands should you have an issue with these buttons.

The D-pad and the start/select silicone pads are great. They feel good, don't move and are reactive.
However, the A and B pads aren't tall enough. The buttons both move freely and rattle. They work well enough, but feel awful.
I have replaced the A and B pads with the grey ones that came with my GBA which still work fine. These were mostly purchased for the stop/start buttons, so not a big loss personally

The clear silicone button pads look great but the issue is the D-PAD silicone button pads. It fits in place but is a bit too stiff. The left side of the silicone button pad is too stiff so I have to hard press it. This makes me want to go back to the OEM pads. All the other pads work perfectly though!

The pads are too mushy and does not provide a tactile response when pressing the button down.

Worked with OEM shell and new shells.

Game Boy Advance Prestige Silicone Buttons