Billie Eilish and her brother (not to mention countless others) recorded everything in their bedroom for their first album. So, if you're recording in a non-acoustically-treated space (bedrooms, closets, etc.), a Reflexion Filter helps keep your signal clean without the sound of your room around it.
The X1 S Studio Bundle has everything from the Vocal Pack, plus SE Electronics' simple and effective RF-X Reflexion Filter so you can record anywhere you want.
X1 S Microphone
RF-X Reflexion Filter®
sE Isolation Pack (with pop shield)
3-meter mic cable