21" WE 600 Series Full Extension Soft-Close Undermount Drawer Slide Box of 6 WE Preferred 0684250504961 6

I've used Blum slides like this but tried these and they are very good. My guys say they are actually easier to install. The sliding action may be not quite as smooth but it's hard to tell and my customers wouldn't know the difference. With these they can get soft-close drawers without breaking the bank.

Advantages: The price
Ease of installation
Disadvantages: The clips seem cheaper but you only clip it in once.