TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The polyfluoro dialkenyl compound (A) is compound having branch structure of formula (I).CH2=CH-(X)a-Rf1-(X')a-CH=CH2 (I)X = -CH2-, -CH2O-, -CH2OCH2- or -Y-NR1-CO-;R1 = H, (un)substituted monovalent hydrocarbon or divalent group of formula (a);X' = -CH2-, -CH2O-, -CH2OCH2- or -Y'-NR1-CO-;Y = -CH2- or divalent group of formula (a);Y' = -CH2- or divalent group of formula (b);Rf1 = group of formula: -Cx-F2x(OCF2CF(CF3))uOCF2(CF2)wCF2O(CF(CF3)CF2O)v CxF2x-, or divalent group of formula: -Cx-F2x(OCF2CF(CF3))y(OCF2)z OCxF2x-;u, v = 1-150, and sum of u+v is 2-200;w = 0-6;x = 2 or 3;y = 1-200; andz = 1-50.The organosilicon compound has 1 or more monovalent perfluoro oxyalkyl group, monovalent perfluoro-alkyl group, divalent perfluoro oxyalkylene group or divalent perfluoro alkylene group in a molecule. Hydrophobization-treatment agent of hydrophobic silica powder is 1,3-dimethyl-1,3-bis (trimethylsiloxy)-1,3-dihydroxy disiloxane.    TECHNOLOGY FOCUS - POLYMERS - Preferred Property: The hardenable fluoro polyether-rubber composition has viscosity of 5000 Pa.second or less at 23degreesC.Preferred Component: The cured material of the hardenable fluoro polyether-rubber composition is manufactured by injection molding. EXAMPLE - (In mass parts) Polymer of formula (6) (Q+R was 98) (100) having viscosity of 10630 mPa.second, and processed silica powder (30) processed using 1,3-dimethyl-1,3-bis (trimethylsiloxy)-1,3-dihydroxy disiloxane and having Brunauer Emmett Teller (BET) specific surface area of 180 m2/g were mix-kneaded, and heat-processed under reduced pressure. Distribution processing of the kneaded material was carried out to obtain liquid base. The obtained liquid base (130), crosslinking agent (3.3) of formula (15), controlling agent (0.3) of formula (16) and chloroplatinic acid/vinyl siloxane complex toluene solution (0.2) having platinum content of 0.5 mass% were mixed to obtain hardenable fluoro polyether-rubber composition.    A cured material of the hardenable fluoro polyether-rubber composition was formed, and had hydrophobization degree of 72, and favorable heat resistance, chemical resistance, solvent resistance and low-temperature characteristics.