A spacer is a hand-held, portable valved holding chamber (VHC), that is placed between a metered dose inhaler (pMDI, or “puffer”) and the user’s mouth, to function as a reservoir from which an aerosol medication is dispensed to minimize delivery of large aerolsilised particles. The oapl Space Chamber contains a one-way valve behind the mouthpiece which is based on Cross Valve Technology™.