Estes A8-3, B4-4, B6-4 Mini Bulk Pack - 9 Engines/Motors with Starters
Brand: Generic

This combo pack provides 3 each of the most popular Estes engines for use in most model rockets. The B6-4 is a medium impulse engine that delivers high altitude flights. It works great for launching larger, heavier rockets, too. The B4-4 model engines which is suitable for use in rockets weighing roughly between 1 and 2 ounces which is typical of most rockets being 1 to 2 feet tall. The A8-3 is a single stage engine designed for model rocket flight. It is a standard engine designed for flights in rockets weighing less than 3 ounces, including the engine.

All the engines you need for low and medium altitude model rocket flights
The best way to get engines in bulk without having to buy 24 of them.
Estes engines are the model rocket industry standard