I purchased two door kits and tunnels with connectors plus one angled connector. After trying a DIY version with drainage pipes I invested in the purpose-made kit by Omlet. Initially I thought the price was expensive however for the ease of use (closing the doors at night); cleaning and free to roam benefits from hutch to outdoor run it gives my guinea pigs, I cannot put a price on. Delivery and communications with Omlet were excellent. Not everyone can afford but if you can do so as animals confined to little hutches sold by pet shops is a depressing thought.
We have some very happy guinea pigs and I am so pleased with this system. Guinea run fast up and down the tubes and LOVE how much more space they have. I LOVE the fact that they spend most of their time outdoors and snuggle back in the warm when they want. VERY happy customer. Thanks