What is "teaser image"? It is asked by a journal in a revision request. The only info that I was able to find is at this link:
Please identify a teaser image from your manuscript that may be used in the abstract book as part of the OnlinePlus program and send this information via email to the publication's administrator. Note that failure to include this information will cause delay in posting/processing your manuscript for publication.
P.S. My manuscript is theoretical.