These are several flavors of the piece of the SDXL Refiner model that Mochi Diffusion needs to turn a SDXL Base model into a combined Base + Refiner model.
Put the correct version of the UnetRefiner.mlmodelc in with the rest of the pieces of your Base model. Mochi will automatically recognize the 2 Unets as a combineed model.
It will use the Base model Unet for the first 80% of the steps and then it will automatically switch to the Refiner model Unet for the final 20%. The transition point is hardcoded.
Take care when unzipping after downloading as they all unzip to the same UnetRefiner.mlmodelc name.
Keep in mind that the Refiner is a generic type model and using it with a Base model that has a specific "personality" might ruin rather than improve images.