Bleed Kit

The reviewer uses a bleed kit (an AliExpress EZMTB Shimano-compatible mineral oil kit) to fill and bleed the brake lines on an AliExpress gravel bike build. He attaches the supplied funnel to the brake lever with the included screw and uses a syringe with tubing at the rear caliper to draw oil through the line until no air bubbles remain. He notes the funnel was specially ordered and came with the bleed kit, and reminds viewers to remove the brake pads and insert a bleed block before bleeding to avoid compressing them or getting oil on them.