Jet of BL Lac at 86 GHz observed by the GMVA on 24 April 2021. The color scale and contours show the total intensity structure of the jet (natural weighting). The contours increase by a factor of 2 from 0.6% to 76.8% of the map peak (∼0.77 Jy beam⁻¹). The gray circle at bottom-left denotes the restoring circular Gaussian beam of 0.07 mas (=70 μas). The green and blue dots indicate the ridge lines measured with the model-fit and CLEAN maps, respectively. The yellow dashed line points to the direction of the known jet component B15 presented in Weaver et al. (2022).