If you're familiar with Go Cat Da Bird with its quality construction and realistic flight, then you absolutely need to buy this.
If you're not, this feather attachment is leaps and bounds better than knockoff versions, with quality construction and lifelike flapping and weight.
This is more durable than knockoff Amazon feather toys, but its still relatively fragile as its a feather. It won't last long if your Cat actually catches and starts biting the toy. Can extend the life of this by not letting your Cat actually catch it.
Definitely buy this refill if the original attachment from the wand + attachment wears out and you need to find replacements.