Enhancing the usability of existing18"d setups, these chrome wire shelving add-on units are an excellent solution for evolving storage needs. Attaches to existing starter unit to extend length of shelves for more storage space Durable chrome-plated steel construction 800 lb capacity shelves can be adjusted easily in 1" increments along posts Made for indoor use, dry storage only S-Hook 2-Packrequired per extra shelf To securely set or quickly remove shelves, tap their corners with arubber mallet. View ourWire Shelving Size Guideto see actual outer and inner dimensions.