These scaffolding brackets are 18.5 cm in length, a parameter that does not include the cast iron flanges and their hexagonal brass bushings, which together sit Ca. 2 cm from the wall; giving a combined 20.5 cm protrusion. 

Each scaffold shelf bracket has two round cast iron wall mounts flanges with a diameter of Ca. 7cm. The width of the screw you use should ideally be 5 mm; the screw length will depend on the wall type the industrial shelf brackets are going to be fixed to. Personally, and this isn't a recommendation as brick/plaster wall compositions vary, I like to use 5 x 40 mm multi-purpose screw along with a 3.5-5mm (red) raw plug; whose hole has been made by a 6 mm missionary drill bit. 

Decorative hexagonal solid brass bushing bolts the copper piping to the cast iron flanges. They shall arrive already mounted and bolted tight with the three holes configured in such away that the industrial shelf brackets can be easily fitted.

A pair of copper saddles and wood screws will be sent with your order; these should be used to fix the scaffold shelf brackets to your wooden shelf: please see image above. 

If you require a larger or shorter scaffold shelf bracket then please email me for a quote; as a ruff ball figure I usually charge an extra £2 for a pair of custom cutting. 

Thanks for looking and please take a look at my other items for sale: like some of the industrial brackets in the last image. Numbered from top to bottom #1 through to #4.