In looking at the description for both of the products that you have referred to, I can clearly see an invalid character in the last sentence for both products. It appears on the screen as a square ( ) within the text. A square ( ) is not a valid English character that can be found on your keyboard. Valid English characters are the letters a thru z and the numbers 0-9. You can also use all of the typical formatting characters that you find on your computer keyboard such as '"()*&^%$#@! and the like.
A square ( ) is just not part of the English language character set, and Ebay is refusing to post your listing because you are using a character that is not part of the English language.