Best type of pen/ink for addressing invites?

I'm going to hand-address my invitations. I bought a template on for keeping the lines straight. For the people who hand addressed envelopes, what type of pen did

Best Calligraphy Pens to Write on Wedding Envelopes

How To Address Envelopes with Cricut - Tastefully Frugal

Cricut Writing and Pen Tutorial: Tips and Tricks - Jennifer Maker

Etiquette 101 - Addressing Your Wedding Invitation Envelopes - CalliRosa - Calligraphy and Custom Design

5 common mistakes when mailing & addressing wedding invitations

How to Address Guests on Wedding Invitation Envelopes Wedding invitation etiquette, Addressing envelopes wedding, Addressing wedding invitations

Gejoy 7 Pieces Envelope Addressing Guide 4 Style Addressing Stencil Templates for Envelopes with 2 Size Brush Pens, Making Thank You Card, Festival

Handwritten or Printed Wedding Envelopes: What's Correct?

The Best Calligraphy Pens and Inks for Beginners