Can NFL teams wear different helmets?

Related questions

1. What are Eagle colors?
2. What color green do the Philadelphia Eagles wear?
3. Will Eagles wear kelly green again?
4. What football team is green and gold?
5. What shade of green is the Eagles?
6. How do I identify an eagle?
7. What color is Cowboy blue?
8. Are Eagles endangered?
9. How many Super Bowl rings did the Eagles give out?
10. What color best compliments gold?

Tags

1. #browns
2. #safety
3. #their
4. #uniforms
5. #player
6. #throwbacks
7. #throwback
8. #ceased
9. #however
10. #regulations
11. #helmets
12. #teams
13. #wearing
14. #season
15. #about
16. #anniversary
17. #began