A polymer preparation consisting of silane-functional polymers, including at least one polymer having at least one terminal group of formula (I) and at least one further silane terminal group, a method for producing the polymer preparation and a composition containing it. The polymer preparation has a surprisingly low viscosity, cross-links surprisingly quickly even without the use of EHS-critical catalysts such as organotin compounds or DBU, and hardens into a non-sticky material with good strength and elasticity. It is especially well suited as an elastic adhesive or sealant or as an elastic coating. The invention further relates to a method for lowering the viscosity of a polymer having at least one terminal group of formula (I) by introducing at least one further silane terminal group.