Which HP laptops does this adapter fit?

It fits HP business laptops that use a 65W, 18–20V, 3.75A supply with the matching barrel connector, such as many EliteBook, ProBook and ZBook models. Check your model's rated wattage and plug size before buying.

Can I use it on a laptop that came with a 45W or 90W charger?

Use the wattage your laptop specifies. A 65W unit is right for 65W machines; a 90W laptop may charge slowly or refuse to charge under load, and a 45W machine should use its own lower-wattage supply.

Does it work with USB-C laptops?

No. It uses a barrel connector, not USB-C, so it won't power USB-C-only HP models or charge phones and tablets over USB-C.

Is this an original HP part?

The part number 709672-001 is HP's designation for this 65W adapter. Confirm the seller lists it as a genuine or HP-compatible replacement before ordering.

Typically just the adapter and its attached cable. Power cords and separate tips are usually not included unless stated, so check what your setup already has.