This is an excellent product.

The ordinary sleepsack with internal sleeves:
https://winterfetish.com/products/darlex-sleepsack

The sleepsack with straitjacket arms:
https://winterfetish.com/products/darlex-sleepsack-with-straitjacket-arms

I have the first one. My record for staying in it, while wearing a diaper, is 12 hours. This included a two-hour nap in the afternoon.