I second this. Just got two chipped 970 Redbox batteries on sale dirt cheap I bought them without really thinking and they share the voltage as well as the physical size of the contacts / locking grooves with the original Canon BP-975s (telling from photos, the bottom side of the battery looks identical). Could it be that it's 975 with the power tester button / LED indicators and 970 without it?
Would be a bummer if there's some sort of functional difference between 970/975 except the power indicator.