Methods of stimulating subterranean formations are provided. The head or the base of the locking device includes locking fingers that allow the head and base to lock together in a one-way snap fit connection. A triggered progressive game includes player-selectable elements, each of the player-selectable elements being capable of association with a progressive-winning outcome. The first lens group has an imaging optical axis and a first effective refractive power. The ion conductivity thereof is also high. The compounds are useful for the treatment andor prophylaxis of diseases which are associated with DPP IV, such as diabetes, particularly non-insulin dependent diabetes mellitus, and impaired glucose tolerance.