2-IN-1 Manual & Electric Knapsack Sprayer State-of-the-art technology, dual function sprayer, Electric + Manual in one unit. Manual spraying is possible when the battery is low. How to Assemble 2-in-1 Battery&Manual Sprayer Assemble the Electric Knapsack Sprayer step-by-step: 1. Take out and check the accessories inside the tank 2. Install the speed control button and waterproof cover as shown in the video. 3. Install a Manual Air Pump, and attach the handle, rod, and nozzle. Don’t forget the gasket. 4. Install the strap, cover, and other components.