My first proper shuttles are made by Milward. They are bobbin shuttles, with a crochet hook and a tail for winding the bobbin. People call them Aero copies. Bad Aero copies. They have all the symptoms: jaggy edges in the plastic, bobbin not fitting on the tail and some bobbins fitting a bit loosely.
But these were quite my only immediate choice. Most of the time the shop assistants had no other brands or no idea what shuttles were. Milward are great, don't get me wrong. Most of their needles are very good for tatting and they usually have good quality products. But these shuttles had to be adjusted.