Keep your rig quiet and isolated with these washers
I purchased these shoulder washers as I was redesigning my rig and striving to minimize any issues with buzzing and hum that may have occured from my rack gear being grounded to the rack rails. I considered the isolation tabs, but visually, it's not the best. Then I found these shoulder washers that do the same job without the visibility of tabs everywhere. They do a great job of isolating not only the rack equipment from the rails, but also isolating the screw from the rack faceplates. This is important, as the conductivity through the screw to the rails may introduce possible hum through the system. These are not always necessary, but it's just extra security that will help in keeping your sound clean and clear, especially when building large, complex rack setups.