*** Please allow up to three weeks for delivery ***
The Petsafe 940US Staywell Tunnel Extension for 900 Series is used with the 919 4-way locking cat flap only (model 919US). Tunnel sections may be stacked to convert the 919 into a 'self-framing' pet door to any thickness. Tunnel sections are 7/8 inch thick. Use as many as necessary for your particular application.