With a one-way valve to prevent the discharge of oil reflux. Easy to install and use. Save energy and protect clean environment. Matching distributor: PV series connector. Matching measuring parts: DPC.DPV series. Oil viscosity: 32-250cST Note: HYA/HL can only press the handle once when filling oil. After the oil supply is completed (the handle recovers by itself), the next action can be carried out to avoid damage to the lubrication pump parts.