Part #1- Measures 18″ wide opening, 10″ deep opening and is 4 1/4″ wide at 1″ down and 5-7/8 ” wide at 10″ down from top. This is a do-it-yourself step-through bathtub conversion kit. •Most KITS have an 18″ opening but a few have a 24″ opening. Some are 10″ deep, others are 9″ deep but some are shallower. See list in pictures or contact me with measurements and I can pick size for you. DO NOT JUST PICK THE FIRST PART. IF you want to pick a part be sure to pick one with measurements larger than your bathtubs measurements, especially on the 1”measurement. Smaller WON’T fit • This saddle Will work on almost any bathtub including Fiberglass and Cast Iron Bathtubs. •We have over 60 different size molds for making parts from. These are shown in sizes on the 3 pictures. •You will need to measure your bathtub prior to ordering. THIS IS IMPORTANT. See pictures for measuring tool and how to measure instructions. Contact us with your measurements if you want us to pick item for you. •All our parts are made of Quality Fiberglass with a Gelcoat Finish. •All parts are in color WHITE. – They can be painted with appliance paint to match your existing bathtub color. •No Modification needed to be done to product when you receive it, Just install the part when received.!!! Easiest insert on the internet to install. •After installed all you will need is a Shower Curtain. •You can install this yourself in less time than it takes to watch a movie, unless you have a steel or cast iron tub. those take longer. •We provide the Bathtub saddle and template shown in picture and complete instructions with pictures for how to install this product. •You only need to purchase a Good Waterproof Silicone Adhesive – available at your local hardware store. This is NOT included in our kits. •We don’t manufacture the part until you order it so that we can give you the best fitting product. It typically takes 2-3 business days to make the part before we can ship it to you.