the mower comprises two rotary mowing heads a first head 10 being a single blade head to trim the vegetation on the inner side of a post supported fixture such as guardrail fence or other type barrier a second head 11 is a multi blade mower head to trim the vegetation between and behind the previously described posts the mowing heads are supported and carried on a trailer type frame 12 as illustrated in fig1 the frame maintains a uniform height of the mowing heads above the ground a unique feature of the frame is the ability to maintain a uniform horizontal relationship of the mowing heads and the posts this uniform relationship is maintained by pressure wheel 13 a pressure wheel 13 is illustrated in fig2 along with a support fork 14 and a vertical axle 15 a support fork 14 is supported in a guide 16 illustrated in fig3 guide 16 is attached to the right side of frame 12 and normal to its primary horizontal axis support fork 14 will freely slide in guide 16 and both have a rectangular cross section to prevent rotation of fork 14 frame 12 is carried by an axle 17 shown in phantom view on fig3 axle 17 being a conventional steerable type as used on the front of a farm wagon or similar two axle towed unit transport wheels 18 are free to rotate horizontally about the ends of axle 17 for steering wheels 18 are connected by a tierod 19 to maintain a parallel.