The cover letter consists of your detail skills information, this is only the purpose of the cover letter only because in CV/ Resume you are not given the detailed form. that's a reason to have seen the Cover Letter Writing service
, according to; the cover letter should he half of the page or maximum full page. the optimal cover letter length should be 200 - 400, this is enough length because nowadays no one has time to read the whole. structured the cover letter into the short paragraphs. and bold the important thing, also and important to use keywords.