About the BX1 Safety Gate Extension: Perfect for wider openings. A 10.5 inch width extension that works with Cardinal Gates Stairway Special (model SS30), Outdoor Safety Gate (model SS30OD), and Auto-Lock Safety Gate (model MG15). Easily attaches to your pet gate for simple installation. About Cardinal Gates: We've been dedicated to making homes safer since 1993. Over the years, we expanded from the original Hearth Guard to a full line of safety gates for children and pets. We have been a member of JPMA for over 25 years and all of our baby gates are certified annually. We are here to help make your home safer.