This is for a letter written by the attorney to your landlord when your landlord does not yet have a lawyer to represent them. After you have had a consultation with your assigned attorney, this letter may be the recommended next step. For example, it could be used to demand a refund of your security deposit, tell the landlord to stop entering your home, challenge a threatened rent increase or eviction, or formally request repairs to be made.
Typically, it is a letter sent by you, but written by your lawyer, so it is correctly stated and includes what needs to be said. If the landlord gives the letter to his lawyer, that lawyer will recognize that it was probably a lawyer that knows what they are doing who drafted this letter, not you. Since the CalTenantLaw lawyers are well-known in California, we want to remain as your secret weapon as long as possible, in case the dispute comes to a lawsuit.
Unlike the complex letter, Item #111, this letter is focused on a single issue, like the examples above. It is intended to solve the dispute as you want, but it will at least lay the groundwork for a strong position in court if the dispute continues to that level.