This is the famous Ona Liquid in the 4L concentrate size. This odor control will help control all your odor concerns. This semi-solid block of ONA (Odor Neutralizing Agent) slowly releases Ona to eliminate any airborne odours. Ona was designed using scientific principles of molecular bonding. ONAs active ingredients come from a blend of 32 essential oils and plant-derived compounds that bond with and neutralize a wide array of odors. When ONA Gel dries out, renew it with ONA Concentrate.