Ring size and height probability distribution with 1σ, 2σ, and 3σ confidence levels, based on the MCMC results (Fig. 9, for Model 2a) extended to lower heights. The color scale shows the probability distribution. The dashed lines show combinations of h and x corresponding to constant polar angles, θ. The black region is limited by the BH event horizon, the gray region denotes RELXILL parameter grid limits.