Designed and manufactured by CagesByDesign.com specifically for use in our enclosures. It solves the problem of getting cords for internal accessories outside your cage and at the same time can be used as an adjustable air flow vent. Fits zero to five cords and allows as little or as much air flow as you wish. The part can be fine tuned for any combination of these two features! It also securely fastens in place so your animal can not escape. Tell us where you want them installed and we will drill the holes for you for free (we can not install in acrylic). Recommendation: Place one in each corner of the back panel (scatter more alone the top and bottom if more ventilation is desired). Hot air rising will pull fresh air into bottom of cage and push old air out of top. Use adjustment on vent to regulate air flow. This formation will also allow cords for accessories or light fixtures anywhere inside the cage.