@Sidewinder Ah, most of them or later ones, yes, but there was a type, the Sinclair ZX I think from memory, that used very much smaller cassettes. I don't know if they were unique to that computer or were used on others, perhaps by other manufacturers.
I had one, given to me by a friend, complete with a box of Sinclair enthusiasts' magazines full of readers' contributed programme lists in Sinclair's edition of BASIC (which I had some knowledge of), and Assembler code (which I knew nothing about).