The rear roller extends right to the edge of the cutter deck so you can mow along borders without any fear of the mower tipping into the lower border. Hyundai hym430sper petrol self propelled roller lawn mower 42cm elec start the hyundai hym430sper lawn mower is a rear wheel drive, self-propelled mower, powered by a hyundai 139cc 3.7hp ohv 4-stroke economical petrol 4 stroke engine.