You can buy them seperately https://www.amazon.nl/GeeekPi-Converter-Stapelbare-Koelventilator-inbegrepen/dp/B08CKDHWCY. Seems like they’re out of stock at Amazon US, but Amazon Netherlands (where I am from) and other webshops still have them in stock. The product is called “GeeekPi 2Pack TF Card Converter for Raspberry Pi Rack Case”. They look like this
