问题：

[问答题]

Write a letter in 130-150 words.
Write a sales letter to an old customer who placed an order with you two years ago,and draw his attention to some new products which represent a great improvement on some of the models he has sold successfully.Your
letter should cover the following particulars:
·对方是你公司的老客户，曾大批订购你公司生产的开关装置（switchgear），之后就没有再订过货。
·告知客户你公司最近在市场推出一种最新高压（high voltage）开关装置，并介绍新产品的特点。
·随函寄上产品规格及价格表供对方参考，并强调尽快订货的重要性。