The print heads do not have # and letters on them for the head ranking, why is that?

www.Sign-in-Thai.com, It is the biggest online supplier of sign products in Thailand and specialized in providing One Stop Solution for customers to select AD equipments, AD consuming materials, sign exhibition products, etc. We have set up overseas branches in 6 foreign countries in order to provide better service for our customers all over the world. Our products cover all field of the AD and signage and all the products we supply are made in accordance with international quality standards as a result that, at present, we have more than 9,000 products online for sale. Since we implement the centralized purchasing, all the products are quoted with competitive prices and good quality.