Our Tube necklace is available in three different adjustable lengths: 16.0 - 18.0", 18.0 - 20.0", or 20.0 - 22.0". The model is wearing the most popular 18-20" length at the longest setting. The circular tube pendant piece measures 5mm by 5mm. Materials: 14k gold, 14k gold-fill (14k gold over brass core/no nickel) or sterling silver (.925). All materials are hypoallergenic. This necklace was designed for Design Lab's second capsule collection in Asbury Park and is handmade in our Upstate New York production studio.