Nutrient frames were used to carry around ysalamiri without them dying. They were made so that they could be carried attached to someone's back without being a hassle.
These frames would supply the ysalamiri with nutrient-dense material in order for them to not go hungry and die on the field. The frames were primarily used by stormtroopers to ensure safety from Luke Skywalker around the year 9 ABY. The frames had to be routinely refilled with the nutrient dense materials every few weeks, lest the ysalamiri run out of nutrients and starve.
The Empire of the Hand was also known to use these devices in their fortress on Nirauan.