On my wife's touring bike it uses a Rohloff with an 8 speed chain. Along with sliding rear dropouts I use a half link to dial in the chain length. I want to get a spare for the kit but seem to be run into a width problem. Wondering if anyone has a better understanding of what size to use?
Thanks!

The width just needs to match the chain you’re using. Usually will be either 1/8” or 3/32” for an internal gear setup. But why would you need a half link with sliding dropouts?

Half links can be used to fine tune the position of the BB (as with eccentric) or the rear axle (and thus rim WRT brakes) to suit those aspects best set up. Seat set back and brake pad location in the arm can be juggled. Andy

I went back out to my shop and git out the calipers again and remeasured. I had 2 half links of different sizes both from QBP. I "think" my last one was labeled incorrectly so I am reordering.
Andy you are spot on -I do it to fine tune the chain length.

I’m familiar with half links but what I’m wondering is whether they’d add any adjustability with sliding dropouts? Couldn’t the dropouts be used to do any fine tuning a half link could do?

EDIT: never mind! I was having trouble visualizing but I do see how the half link would give finer tuning of chain length.