The sitting box is exactly what the title suggests, a box that is padded and upholstered ,which can add a great deal of comfort to many Pilates seated exercises.
You can use the sitting box with your reformer to add more exercises. These include more prone exercises, abdominal exercises and it’s really helpful for side stretching. For many people the sitting box makes prone exercises like the swan more comfortable as well as supine exercises like the back stroke.
If you want to use the box primarily with your reformer, there's a number of things you'll need to check.
Look and pay for a quality steel frame. Also look for at least a 15mm birch or marine ply which will give you maximum strength and durability. The box will get used extensively and has to take your full weight as you sit or kneel on it.
When you buy your box, check the cover is an abrasion resistant vinyl. This will prevent easy tears as well as allow you to wiped down with anti-bacterial wipes or just to sponge clean if it's for using at home.
Look for the hand straps that enable you to move your box about easily as well make it easy to store at home. Some also come with a foot strap to help some of your exercises - where you need to anchor yourself.
First and foremost ensure it's compatible in terms of it's width. Sitting boxes come in different sizes so do check all dimensions if you are extra tall.