Guide bars are not very strong or rigid. I figured maybe I didn't install it properly, but when I tried to put the rail in without the drawer I had trouble getting in because it's very loose in the front making it prone to breakage. Ball joints fell out of one during installation. So frustrating. I've installed a lot of ball bearing guides with no problem, it's not good. Also, there are no vertical slots on the outside of the roller shutter, only horizontal ones. Installing drawer slides is no fun, but hardware issues make it a nightmare.