Thimble is a small hard pitted cup worn for protection on the finger that pushes the needle in sewing, quilting. Many types of needles are made from metal or harden or ergonomic moulded plastic and some are adjustable.
Hemline metal one with non slip tops to help push the needle through your fabric. These are on cards which you can try size before opening the thimble.
Prym ergonomic thimbles are breathable thimbles which mould round your finger while you are working and still protecting.
Clover Adjustable thimble ideal for when doing Sashico needlework