Is the Brake hose cover long, rubber compatible with DN 3 Teflon brake hoses?

Yes. Brake hose cover long, rubber is compatible with DN 3 Teflon brake hoses. The product description explicitly states it is a protective grommet intended for DN 3 Teflon brake hoses and the material is rubber, so it fits and protects that hose diameter.

Can the Brake hose cover long, rubber protect DN 3 Teflon brake hoses from dirt and moisture?

Yes. The Brake hose cover long, rubber is a protective grommet designed for DN 3 Teflon brake hoses and is made of rubber, so it will shield the hoses from dirt and moisture. It fits over the hose to provide a physical barrier against contaminants and offers some protection from water ingress and abrasion. Note that while it significantly reduces exposure to dirt and moisture, it may not be fully watertight against prolonged immersion or high-pressure sprays; for those conditions additional sealing or housings may be needed.

Does the Brake hose cover long, rubber fit over connectors on DN 3 Teflon brake hoses?

Yes. The Brake hose cover long, rubber is a protective grommet intended for DN 3 Teflon brake hoses and is made of rubber, so it fits over the hose connectors. It slides over the DN 3 Teflon hose ends to provide abrasion protection and a snug cover around the connector area. Make sure the hose diameter and connector geometry match DN 3 specifications for a proper fit.