Hope you are doing fine.
Let me tell you about your first listing. There are some changes you need to do.
Consider these points and make changes in your listing accordingly.
1)You need to add more images to your product listing. Amazon allows 8 images to upload.
2)Create more bullets points with relevant information.
3)Some of the keywords you can include in your title, bullet points and lower area. You can also take help from our newly launched keyword research tool.
towel bar holder
towel rod for bathroom stainless steel
towel rod 18 inches
towel rod stainless steel
As people also searched for towel rod as well as a towel holder.
4)It is suggested to get some quick friendly sells and reviews to get some early matrix which can help to get improve product visibility.
5)You can make set of towel bar and create new listing.
E.g. towel rod set of 3, towel bar set of 5 etc.
Q)I have already same product of length 18 inches So how can I add variation in this?
>>>You can use UPC code to add towel bar of 18 inches by creating new listing with same brand name.
Let me know if you need help with anything else!