High resolution (1′→0′.1) maps of the outer complexes of some “well formed” powerful radio sources suggest that we can now distinguish two physically distinct types of outer hotspots. We denote them as type “A” and “B” and describe them as follows: Type A hotspots, illustrated in Figure 1, occur at the outer leading edge, and have a cusp-like, or otherwise elongated shape. This strongly suggests that their shape and energy density are determined by the ram-pressure interaction between the end of a beam or momentum flux “pipeline”, and the ambient i.g.m. Magnetic fields appear well-ordered along the cusp (Laing, 1981). The surface brightness of well-resolved Type A hotspots leads to a velocity of advance (Va) which is typically 103→104 (ρ−1ig-27)km/s (ignoring the ion energy).