Contractions of affine spherical varieties

The language of filtrations and contractions is used to describe the class of $G$-varieties obtainable as the total spaces of the construction of contraction applied to affine spherical varieties, which is well-known in invariant theory. These varieties are local models for arbitrary affine $G$-varieties of complexity 1 with a one-dimensional categorical quotient. As examples, reductive algebraic semigroups and three-dimensional $\operatorname{SL}_2$-varieties are considered.