Bottom Roller RD118-21700 KX121-3 Fits Kubota Bottom Roller Sale Fits KubotaOne New Aftermarket Replacement Bottom Roller RD118 21700 Fits Kubota Mini Excavators This aftermarket track bottom roller (also known as a track roller or lower roller) is a key undercarriage component Fits Kubota mini excavators. Mounted along the bottom of the track frame, it supports the machine's weight and guides the rubber track, maintaining proper alignment and smooth travel across all terrain types. RD118 21700 supersedes the earlier OEM