Nagaoka - CW-402 - Pocket Winder
This little gadget allows you to quickly wind a cassette without having to put it in a deck.
It's noisy, it's rough, but it works and is very convenient.
PLEASE NOTE: This is a sealed electronic item that is decades old, if you would like me to open it up to check it works, please put a note on your order. If not, I will ship it still sealed, but will not accept returns if it turns out not to work.