h
The bandwidh value. It can be a single value, which is turned into a vector and then into a diagonal matrix, or a vector which is turned into a diagonal matrix.
thumb
Do you want to use a rule of thumb for the bandwidth parameter? If no, leave it "none", or else put "estim" for maximum likelihood cross-validation, "scott" or "silverman" for Scott's and Silverman's rules of thumb respectively.