(Edit; I had posted this elsewhere but moved it here; it didn't belong where I first put it). Over the years Penn has made conventional reel spools in several designs. There are metal and plastic. There are 3-piece, cast brass, some with drilled arbors and some with line ties. Is there a thread here somewhere that discusses spool design and the differences between the different designs, and about when they were introduced? If not, can this be the start of one?
Sid
What Penn currently makes now they call it "live" spindle spools (in Squall, Fathom, etc). It is where the bearings are inside the spool and the spool is independent from the shaft. Its not really new technology since Abu Garcia done it for the C3s etc.
-advantage(s): better casting due to better free spool
-disadvantage(s): for some reels, using heavy sinkers (greater than 3 oz) you have to cock the spool backwards to disengage spool.
Other spools are fixed spools (jigmaster) where the shaft is permanently fixed into the spool. These don't cast as well because the fixed shaft adds additional friction points (ie inside of the pinion gear).
Also, I've noticed on some spools (mostly graphite) that the ends are really wide. I'm guessing that people use that area to thumb brake there instead of on the line.