Name of Sender,
Address of Sender,
Name of Recipient,
In the first paragraph you need to make aware to the recipient about your inquiry you are going to make through this letter. You can tell here exactly about what you need to inquire about.
In the second paragraph you need to ask various questions regarding your inquiry. The questions can be in respect prices, type, and various other things if you are making inquiry about different products. You need to be very specific about your inquiry questions.
In the last paragraph you need to request for the earlier and prompt reply for the inquiry so that you can get earlier response. You can also ask for various details if the recipient is ready to provide through various means such as through sms or through email. You can also provide the address and contact information where you can get response.
Name of sender