Country Manor Wall Units Provincial Stone Curbstone Keystone Standard Units Compact Units Victorian Wall Stone Garden Wall Intermediate Units Corners & Caps Retaining Wall Accessories Celtik Wall Keystone Intermediate Units Photo Gallery | Product Colors | Specifications | Installation Guidelines Keystone Intermediate Units have proven to be the choice for do-it-yourself projects. They weigh less than Compac Units and require no pins or special tools to install. Available with either curved or straight face, Intermediate Units are ideal for walls up to 3' feet in height. For more info on Keystone, Click here to visit the Keystone Website