Each Sure Petcare product has an integrated tunnel that is 70mm, which forwall installations is typically not long enough. In order for a tunnel toreach all the way through a customer’s wall, tunnel extenders should beadded to the existing tunnel, each one adding an additional 50mm to thelength.Each Sure Petcare product has an integrated tunnel that is 70mm, which forwall installations is typically not long enough. In order for a tunnel toreach all the way through a customer’s wall, tunnel extenders should beadded to the existing tunnel, each one adding an additional 50mm to thelength.