The tab is a simple shape.  It is round, with straight sides and a flat surface. 

There are 5 sizes in this shape.

Tab Trio contains the 3 sizes that measure:

Mini 13mm x 6.5mm thick

Small 15mm x 7mm thick

Medium 18mm x  8mm thick

Tab Large measures:

24.5mm (1") x 10mm thick

Tab XL measures:

38mm (1.5") x 10mm thick

Fun Fact: This tool works great with the Lentil tools in the corresponding size. If you use the bottom of the tab tools with the top of the lentil tools, you will make a hybrid shape, that has a soft sloping top with a flat bottom. Very cute and easy to wear! You can find the Lentil Trio in the Lentil section of the store.