(Make sure that XENO Modchip or PICO boot has been installed in your console). It is a SD card adapter.
For Nintendo Switch Replacement Micro SD Card Reader Slot Port - UK Stock
SD2SP2 Micro SD Card TF Card SDLoad SDL Card Reader for Nintendo GameCube (NGC)
for Nintendo GameCube - SD2SP2 Micro SD Card TF Card SDLoad SDL Card Reader NGC
Adapter Card Reader Replacement card adapter card reader for sd2sp2 v2.0 Lot V0
Adapter Card Reader Replacement card adapter card reader for sd2sp2 v2.0 New G1
