Thanks to its focus on just a few products, Casper co-founder Gabriel Flateman has seen his company hit $300 million in revenue and take on the mattress industry's giants. Here, Inc. executive editor Jon Fine asks Flateman about dog psychology and how a team of five co-founders really functions.

Why only one mattress?

There's all this choice in the mattress industry and much of it is wildly mundane. When the problem is an overabundance of choices, the answer is pretty simple: Focus on one core thing that works for many people. With T-shirts, I wouldn't advise the same strategy, because there is inherent choice in fashion. It's got to stem from user need. But there is a lot of opportunity, in efficiency and clarity of purpose, gained by making and marketing one product.

Still, there are long-established companies in your business. How do you chip away at them?

We saw a huge need for services like white-glove delivery, mattress removal, and setup. A lot of the incumbents have locked those down as a check mark but not as an experience. So we knew there was a real demand to provide value through small things. And one of the best things about direct-to-consumer is that we have a true relationship with the customer. That's a powerful tool the incumbents don't have, especially on the design and manufacturing side.

Casper now sells a dog mattress, and your company enlisted the help of a dog psychologist in designing it. Why?

One of the things I'm learning is how little innovation effort goes into large-scale product development. And we found a lot of interesting stuff. For example, dogs really like to nuzzle into a little wall. It makes them feel safe. So, after testing with dogs, we picked a design that has a wall. But the real point is, the more you own the experience, the more opportunity you have to optimize and improve.

Casper has five co-founders. Should companies have such large co-founding teams?

Only if they can handle it. It works for us because we have disparate skill sets, and we are focused on and have domain over different areas. It's not as if we are five MBAs with the same skill sets and the same desired job. We debate, collaborate, and challenge one another's ideas endlessly. But if you are worried about stepping on the toes of one or two other co-founders, it will be chaos with five.

Correction: An earlier version of this article misstated Casper's revenue. It is $300 million.