Product review (5 stars): A necessary purchase for self installation of the Aprilaire whole house humdifier
My siblings and I bought my parents the Aprilaire humidifier for a Christmas gift and my brother installed the humidifier using this installation kit.  I ordered the humidifier and the kit.  No complaints from the brother about the installation so I think it was a worthwhile purchase.  I believe he had to buy a few bits and bobs from the hardware store to complete the job.  Apologies for not being able to supply any technical info.