Review on 🐹 DIY Hamster Tube Toy: Assorted Playground Tunnel for Small Animals - Ideal for Mice, Hamsters, and More by Melissa Cook

They have exactly the same diameter as the popular systems used in the title, but the connector system is different. Looks like they tried to mimic the habitrail system lip but made it a little too long. To connect to other systems, you can use the mating rings included in the scope of delivery, but the connection is made freely and is not structurally rigid. The joints are free to rotate about a circular axis, meaning many twists and turns will not hold their shape when mated to more common systems. Their advantage is that they are inexpensive and the quality is about the same as Tiny Tales and SAM whistles. Habitrail and Kaytee are a quarter above these and the two mentioned. Better done but still in the same class. The diameter and functionality are right, but it's annoying that they've made it incompatible with other systems that are all compatible with each other. They could probably be made compatible by grinding the pipe ends, but then it would be more cost effective to buy one of the other brands due to the inflated work. I really wanted to like these tubes because they are slightly different sizes than the others. The incompatibility is a deal breaker and it's coming back.