Left and Right Triggers

Buttons located on the left and right top of the Game Boy. Different games give them different functions.

Plastic

Most of the replacement retailers are based out of Hong Kong and the Guangzhou province of China (the industrial district). Because there are no specific markings on the plastic pieces, we can not trace them back much further than this general region. (Hong Kong and the Guangzhou province are fairly close together.)

Likely the Guangzhou province of China.

These buttons were assembled in a factory in either Hong Kong or the Guangzhou province of China before being assembled into the Nintendo GBA. One of the massive retailers list, "original in China" under the description for their listing of triggers, so we can deduce that the triggers are likely from Guangzhou. (https://www.aliexpress.com/item/20PCS-For-Game-Boy-Advance-Left-Right-Shoulder-Trigger-Button-Switches-For-GBA/32791200914.html?spm=2114.01010208.3.2.CCJ3dI&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10130_10068_433_434_10136_10137_10138_10060_10062_10141_10056_10140_10055_10054_10059_10099_129_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10078_10079_10073_10070_10122_10123_10124,searchweb201603_6,afswitch_1,ppcSwitch_5,single_sort_0_default&btsid=8aaf8507-6dcb-4154-8b35-be4bbb0a2480&algo_expid=301f5e4e-dc71-47bf-99f4-ff0673108667-0&algo_pvid=301f5e4e-dc71-47bf-99f4-ff0673108667)

The triggers are listed as being sold often in Hong Kong and China through large online retailers, with the "original in China." (https://www.aliexpress.com/item/20PCS-For-Game-Boy-Advance-Left-Right-Shoulder-Trigger-Button-Switches-For-GBA/32791200914.html?spm=2114.01010208.3.2.CCJ3dI&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10130_10068_433_434_10136_10137_10138_10060_10062_10141_10056_10140_10055_10054_10059_10099_129_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10078_10079_10073_10070_10122_10123_10124,searchweb201603_6,afswitch_1,ppcSwitch_5,single_sort_0_default&btsid=8aaf8507-6dcb-4154-8b35-be4bbb0a2480&algo_expid=301f5e4e-dc71-47bf-99f4-ff0673108667-0&algo_pvid=301f5e4e-dc71-47bf-99f4-ff0673108667) This leads us to believe that the buttons were likely produced in the industrial district of China, Guangzhou. However, because there are no serial numbers on the buttons, we can not trace their origins back much further.