Will Maltby be thinking about producing heads that would work in same length clubs.  Lie angles, moi, weights would have to be similar through all heads in a set.  I know that One Iron, the single length club maker in Toledo, uses the MPF in reference to how playable their clubs are.  I have made clubs for myself and others for years.  Would love to give the SL style a try but not with the expense of One Iron or Sterling or Edel, as Bryson Dechambeau has done.  Have tried looking for an old set of Armour EQL’s but haven’t found them yet and they are 30-40 year old technology.