First-epoch [S ii] image of the J1 (bottom) and J2 (top) jets and the characteristic sizes of the small-scale features observed in the optical lobes (a_x,k (left) and a_y,k (right)) as a function of position y along the jet axis, obtained from the wavelet analysis. The k = 1 peaks are represented in red, k = 2 in green, and k = 3 in blue. Three examples of the compact knots (K), arc, and leading bow-shock (BS) classes are labeled.