ISKY Retainer Question, 507ST and 507STA 7 Deg Locks

[Hyper_pak]

Not sure if this is the right place to ask, but I figured SBM engine builders might know an answer.
I was on the phone with ISKY yesterday and we determined the 507 retainers are right for my springs.
What they could not answer was "What is the difference in an ST and and STA?"
The STA is, in their database, a +.060 retainer.
They did measure one on it's side and the difference is this.
An ST measures .390 and a STA measures .440, retainer top to retainer bottom.
Trying to wrap my head around what that really means.
I can't take moving the valve tip any lower into the retainer.
But if it decreases the installed spring height that would explain the +.060 number.
Any ideas?
I guess they don't publish, or have, detailed data to keep their competitors from building the same part.

 

[PRH]

Based on what you’re describing, the added installed height of the STA retainer is achieved by raising the position of the retainer on the valve stem, which will have the valve tip lower vs the retainer top……..compared to the ST retainer.

The thing to keep in mind with aftermarket retainers/ locks is……..there isn’t really an industry “standard”.
So a normal installed height retainer from brand A, may not be all that close in installed height to one from brand B or C.