What are these for with replacement clips? 1970 Rear (windshield) glass

[72and86]

1970 Cuda
These 2 red clips came with the rear windshield install clips I ordered. Theres no reference to what they are or what they're used for. Any help?

Any tips installing the 2 glass pieces? Front windshield and rear glass? Tape/ Size?
Thanks

[anlauto]

The red clips screw to the bottom of the channel to support the rear glass from sliding down while curing, or on really really hot days

My glass guy insists on throwing them out and replacing with a small rubber block similar to what's used on the windshield, he can't stand the idea of glass rubbing on steel ...he's been doing glass since 1983