Which end goes inside and which goes outside, no directions?

We have added the instructions for this item to its specifications. Here is what you do:

Determine correct location for wall penetration. Drill 3" diameter hole through wall. Measure wall thickness and adjust wall sleeve to same length up to 7.5". If wall is thicker then 7.5" add sections from a second NFP75 until desired length is achieved on the interior flange place a bleed of caulk or other sealant product and slide NFP75 from the interior wall outward until flange is flush to interior wall surface. Route piping and cabling through NFP75 as needed and complete installation of indoor unit. Using appropriate material seal any gaps in and around the exterior edge of the NFP75 and piping/cabling. If desired some loose insulating material can be added inside the sleeve for better thermal performance of wall structure.

If you have any further questions, please call us and we will be happy to assist you.