Review on 🔗 Ultimate Flexibility: Premium Extender Expandable Elastic America for Unmatched Comfort and Adaptability by Luis Despain

These things work well and not only lengthen the collar but also make it stretchable with elastic. When you turn your head, your collar flexes a little, making it comfortable in multiple positions. I would give 5 stars but I think these things are overpriced for what you get. I haven't tried it more than once or twice so I don't know how they hold up over time.