Your search for "20mm" revealed the following:
Large Black Rounded Toggle 65mm x 20mm - TGB1010
£2.40
These black toggle buttons have one slit centered on the 65mm x 20mm button. Length: 65mm Width: 20 mm Material: Horn
Grey Striped Corozo Button Size 20mm - TGB3066
£3.60
These grey buttons are made of Corozo or vegetable ivory material with a stripe pattern. These buttons have two holes and are 20 mm. Diameter: 20 mm Material: Corozo made from the Tagua nut also known as vegetable ivory
Stone Simple Matt Buttons x 20mm - TGB3023
£0.85
These classic cream matt buttons are made from recycled cotton with four holes for attaching to your project. Diameter: 20mm Material: 80% cotton fibres 5% plasticisers & dyes 15% technical binders
Pearly coral buttons w/ patterned edge x 20mm - TGB4121
£0.90
These coral buttons have an etched pattern on the rim and two holes for attaching to your project Diameter: 20 mm
White and Gold Glitter Shell Button 20mm - TGB2767
£1.00
These white shell buttons have a triangle pattern in gold glitter with two holes for attaching to your project. Diameter: 20mm Material: Shell
Purple with Grey Rim Polyester Button Size Size 20mm - TGB3844
£0.80
These polyester buttons have a purple center with a grey rim as well as four holes to use to attach to your project. Diameter: 20 mm Material: Polyester
Large Black Smooth Rounded Toggle 75mm x 20mm - TGB2269
£2.40
These smooth black toggle buttons have two holes centered on the 65mm x 20mm button with rounded edges. Length: 75mm Width: 20 mm Material: Horn