As Stephen Covey says, begin with the end in mind.
What do you want the audience to leave the presentation with? Take action? Agree to a plan? Buy a product? Use your products?
A recitation of products with detailed information about them could be just as easily conveyed with a catalog or an emailed document. Or provide that detailed information in a handout done in Word or a page layout program, and leave the reasons why in the presentation.
A 20 minute presentation that is focused on answering the audience's question of "What's in it for me?" likely needs 10 slides, maybe less.