Legal analysis: All voluntary commitments are valid. Usually, a contract is required to be concluded in writing, and its promise must also be in writing. The legal effect of the letter of commitment is that once it is made and delivered to the offeror, the contract is established and the offeror shall not refuse it.

Legal basis: Article 490 of the Civil Code of People's Republic of China (PRC). If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.

A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.