TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: (II) is n-butane, isobutane and/or propane, especially n-butane. The organic solvent is an alcohol, specifically selected from 1-4C alcohols, polyols, polyol ethers and their mixtures, especially ethanol. The device contains (I) at 0.5-20 (preferably 2-12) wt. %, (B) at 20-70 wt. %, (II) at 1-30 (preferably 5-20) wt. %, DME at 5-70 (preferably 10-50) wt. %, water at 0.5-35 wt. % and alcohol at 1-70 (preferably 15-65, especially 30-60) wt. % (all based on the overall contents of the device). Composition (A) optionally also contains adjuvant(s) selected from other (non-polyurethane) fixing polymers, silicones (in dissolved, dispersed or micro-dispersed form), surfactants (non-ionic, anionic, cationic or amphoteric), ceramides, pseudo-ceramides, vitamins or provitamins (e.g. panthenol), oils (vegetable, animal, mineral or synthetic), waxes, water-soluble or lipid-soluble, optionally siliconated sunscreens, glycerol, mineral or organic pigments (colored or non-colored), permanent or temporary dyes, pearl-gloss or opacifying agents, sequestering agents, plasticizers, solubilizers, acid or alkali, mineral or organic thickeners, antioxidants, hydroxyacids, penetrants, perfumes, perfume solubilizers, preservatives, corrosion inhibitors and/or active treating agents.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polyurethanes: (I) contains repeating units of formula -X'-B-X'-CO-NH-R-NH-CO- (I') and/or -X'-P-X'-CO-NH-R-NH-CO- (I'').X' = O and/or NH;B = optionally substituted hydrocarbylene, preferably of 1-30C;R = optionally branched alkylene of the 6-20C aromatic, 1-20C (preferably 1-6C) aliphatic or 1-20C (preferably 1-6C)cycloaliphatic type (optionally substituted by one or more of halo, 1-4C alkoxy and/or 6-30C aryl, specifically phenyl), especially hexamethylene, 4,4'-biphenylene-methane, 2,4- and/or 2,6-tolylene, 1,5-naphthylene, p-phenylene, methylene-4,4'-bis-cyclohexyl or isophorone residue;P = polysiloxane segment.(I) is preferably anionic. EXAMPLE - An aerosol device contained 6.00 % (as polymer) Luviset SI-PUR ZK 553-24 (TM) (fixing polyurethane), 0.05 % ethylhexyl methoxycinnamate, 12 % demineralized water (contained in the commercial polymer), 3 % demineralized water (separately added), 0.10 % perfume, 15 % n-butane, 25 % dimethyl ether and absolute ethanol to 100 %. The formulation was sprayed onto hair to provide a mild hair-spray with a very good holding effect.