A moisture curable composition comprises: (A) a polymer containing reactive hydroxyl or hydrolysable groups bonded to silicon which groups are reactive in the presence of moisture; (B) a crosslinking agent comprising at least two groups reactive with the silicon-bonded hydroxyl or hydrolysable groups of polymer (A); (C) one or more reinforcing and/or non-reinforcing fillers; and (D) a silane having the structure (R1)m(Y1)3-mSi—Z1-G1-Z2—Si(R2)q(Y2)3-q. R1 and R2 are alkoxy groups containing from 1 to 6 carbons, Y1 and Y2 are alkyl groups containing from 1 to 8 carbons, Z1 and Z2 are alkylene groups having from 1 to 12 carbons, G1 is a chemical group containing a heteroatom with a lone pair of electrons, and m and q are independently 1, 2 or 3. Silane (D) is present in an amount of from 15 to 30% by weight of the composition and functions as a cure catalyst.