A Tripwire is a low ticket front end product that is so irresistible that people have to purchase it.
After the purchase of the low ticket item, you can up-sell more expensive items through order form bumps and one click upsells.
These Sales Funnels have also been called Self-liquidating Funnels (SLO). With a Self Liquidating offer, the goal is to break even on ad-spend, then ascend paying customers to a higher-ticket offers on the Thank you page and beyond.
3 or more pages: Order Form, Upsell page, Downsell page, Thank you page
Example: Order a BBQ Grill, with lighter fluid as an order bump, then offer a utensil set on the second page as an upsell, and a BBQ cookbook as downsell on the last page. For future communication, they would be subscribed to the "Grillers of the Month Club" receiving monthly updates on new products available for their grille.