The use of the premises shall be limited to storage only, and the premises shall not be used for any auctions or sales, or storage and transfer businesses; for the servicing, repair or fabrication of any vehicle, boat, trailer, appliance, or similar item; or for the operation of power tools, compressors, kilns, or similar equipment; except that limited sales to tenants of products and supplies incidental to the principle use, such as packing materials, identification labels, rope, locks, tape, etc., shall be permitted on the site devoted to this use. The storage of combustible or flammable liquids, combustible fibers, or explosive materials, as defined in the fire protection code, or toxic materials, is expressively prohibited.