ABL for W_H based on HST photometry for the joint sample of Gold cluster Cepheids (N = 15) and the Cepheids in the R21a sample (N = 67). Black error bars are derived using Gaia EDR3 parallaxes of Cepheids, and colored error bars are based on cluster parallaxes. Specific cases are colored individually to help identify Cepheids with cluster parallaxes discussed in the text. U Sgr, S Nor, and SV Vul appear twice in the plot because we use the Cepheid and cluster parallaxes to estimate its ABL. The Cepheids in the Silver sample XZ Car and X Pup are not included in the fit. In the plot, the zeropoint offset of the Cepheids has been already applied.