Twin-Drum Walk-Behind Roller comes with hydrostatic drive system. The ER650 has a high compaction force but is also compact with well positioned controls making it easy to operate. Suitable for a wide range of soil and asphalt compaction applications. The Twin-Drum Walk -Behind Roller comes with hydrostatic drive system. The ERC650 has a high compaction force but it also compacts with well positioned control making it easy to operate. Suitable for a wide range of soil asphalt compaction applications.