Juniper-based network — need Sonicwall firewall too?

Hi, we are setting up a Juniper-based network (2 Juniper EX2200-48T-4G, 1 J2320-JB-SC) for a small office with 6 employees.

Do we need a Sonicwall NSA firewall as well on top of that or are the router’s built-in security features good enough?

Thanks!