These spacers replaced hard plastic ones on my 3D printer's bed (CR-6 Max). This allowed me to fine tune the torque on each screw to gain a level bed (as close to zero as possible!). They are fairly rigid silicone and depending on the quality of the screws in your print bed, it may be worth it to replace those too. Quite a few of mine had stripped due to the poor quality, which is why I figured this is of note...Depending on your printer's bed, these may be tricky to install. With my printer being larger, it was tricky in the sense that they were hard to align all of them up to all the screw holes. Once in, it was just a game of simply torquing each screw one by one slightly until you reach a desirable result. This is definitely a project - so devote a couple of hours to the cause depending on how large your printing surface is.I would definitely recommend these! They have kept my print bed level and have improved the reliability of my 'first layer'.