I want to order new roller saddles for my Yamaha Pacifica strat. I was planning on getting the ones from GFS (link at bottom), but I'm a little confused by the page. They refer to string pitch twice... To measure this, should I measure from the left edge of the leftmost saddle on the bridge to the right edge of the rightmost saddle, or do I measure where the strings themselves are? And as a side question, is it worth the $14? I'm also buying locking tuners and roller string trees because I finally have a tremolo arm that fits. Thanks!

'89 MIJ Fender Strat
Rivera S-120
'60s PEPCO Model 211 5w head
'60s Paul (Pepco) 1x12 tube amp
'60s Harmony H303a 1x10 tube amp