Everything a routine service needs, kept together so nobody has to come back for the washer.
A cycle service kit is an oil filter, a drain washer, a litre of oil and a spark plug, and it is cheaper together than separately. A small car kit adds the air filter and, where it takes one, the cabin filter.
On oil we will give you an honest opinion and it is not always the expensive one. For a scooter doing short trips in this heat, a semi synthetic at the correct grade changed at the proper interval beats a full synthetic changed when somebody remembers. The interval matters more than the label on the bottle.
We keep gear oil in small bottles because a scooter final drive takes about a hundred millilitres and selling somebody a litre of it is selling them nine hundred millilitres of shelf decoration.