The water-durable "Lumi Anklet" from Jenny Bird includes three non-removable extender rings, making it easy to adjust to your ideal length. 

rhodium ion plated steel
stamped pendants
lobster clasp
finish: high polish

product measurements:
wearable at 21.29cm / 8.38", 23.34cm / 9.19", 25.56cm / 10.06", or 27.64cm / 10.88"
chain width: 1.4mm / 0.06"
pendant height: 6.1mm / 0.24"
pendant width: 1.35mm / 0.05"
weight: 2.45g / 0.086oz