That’s the one. And as @nigho said it was needed to avoid the very real pain of injecting with the big glass syringes and significant needles that I remember my parents sterilising by boiling in a pan. I also remember the black box and I’ve stored it somewhere in the house and hope to find again soon.
So who remembers the small chemistry set of test tubes, fizzing tablets and colour charts (was blue good?) that were involved in urine testing for sugar?