In reply to PaulJepson:
Sizes 1 and 2 are still the only device for very narrow parallel cracks other than pegs or newer aid devices like camhooks. You probably know that.
Luckily found those very sizes below a grit crag years ago, posted on here but no response. Email me if you think they were yours.
Never used or carried them.
Only time seen used on the crag, they were the only possibility on a project a friend was trying. It held and prevented a groundfall