Necklace Lanyard Compatible with JUUL, BLU, and other small vape pens. Mini gear bag for lanyard, or cartridges, or charger and cartridges. Easy and simple to use. Imagine Never losing your pen again. Perfect gift idea for anyone that uses a vape pen. Also lanyard holds lighters or Lip Balm. Small ring =10mm (about 3/8”), Large ring = 13mm (about 1/2”)