Canon YB2-0033 Zoom Collar
Genuine Canon Zoom Collar for the EF 16-35 2.8 L USM, EF 16-35 2.8 L II USM, and EF 17-40 4.0 L USM lenses. Package of 1 collar. Made by Canon Japan. The screws used to retain this collar are in stock here.
Canon YB2-0323 Guide Collar
Then use the option option to select from sizes available. 
Canon YB2-0333 Collar Screw
Canon YB2-0411 Lens Mount
Genuine Canon lens mount for the NON CMT (Canon Made Taiwan) EF-S 18-55 3.5-5.6 DC / EF-S 18-55 3.5-5.6 II / EF-S 18-55 3.5-5.6 USM and EF-S 18-55 3.5-5.6 USM II lenses. Please note: Look on your lens mount and if "Made in Taiwan" is not printed there, you need this lens mount. If your lens mount does show "Made in Taiwan" you need the lens mount listed here. This mount only fits lenses listed and does fit any STM lens. Ironic this lens mount is Made by Canon Taiwan.
