Brief differences between P77STFLXA and P77STFLXB and also details of P75LRST probe tip

From the P7700 Series documentation I have found specification for P77STFLXA and P77STFLXB solder in tips. I have below queries, please clarify.

* What is the difference between P77STFLXA and P77STFLXB i.e A & B. Why espicially mentioned A & B at the end of the model name.
*For P77STFLXB, In P7700 Series documentation I have found that we can use for Flex circuit based DDR4/LPDDR4 memory solder in tips. Specifically mentioned DDR4 but for P77STFLXA they didn't mention any DDR4 like that. So can you briefly explain why and confirm whether we can use that for LP-DDR4 3200.
* What is the specification of P75LRST, especially temperature range and also please assist me to get a datasheet of P75LRST probe tip.

Hello! I believe I can be of assistance here since you've been left without a reply for a few months now. I'm going to assume you wanted to know about the P75TLRST as there's no P75LRST variant. The P75TLRST is capable of 20GHz bandwidth (which depends on the probe you're using) and there is a P75PST performance tip that is advertised up to 30GHz of bandwidth at the cost of being shorter than the P75LRST probe tips. I'm guessing these are able to operate from 0C to 40C, similar to the probe's operating range. if you want higher temperature, you'll need to switch to the high-temperature tip which can go from -55C to 150C (assuming you keep the probe properly heated/cooled (depending on environment)). The P77STFLXA is a flex probe tip with 175 Ohm resistors placed at the tip. Excellent for mid-bus probing and anywhere else you feel like you want to probe some signals. The P77STFLXB is a flex probe tip with 75 Ohm resistors placed at the tip and is designed for use with the Nexus Technology interposers that have an embedded 100 Ohm resistance on each line (hence the 100 Ohm difference between probe tips. NOW I must stress this: the P75LRST is NOT compatible with the P7700 series probes that the P77STFLX A and B variants use. I've used both probes and feel like the P7500 is MUCH better for the end user as it offers a LOT more forgiveness when it comes to placing and attaching probes, especially around a DRAM interposer (I lost two interposers because the pads were ripped off when I was installing the P77STFLXB probe tip into the P7716 probe). I've done a LOT to secure these probe tips, but only so much can be done before you ask "what flexibility does this actually offer? Is it flexible in the sense you can 'shape' the probe tip without breaking it because it certainly isn't forgiving to motion." Another wonderful thing that the P7500/P75LRST offers is a SMALLER footprint that the P7700 series probe tips take up. The P77STFLXA/B is 6.35mm wide while the P75TLRST is only 5.08mm. This is a BIG problem when you're using the Nexus Technology interposer OR probing tighter spaces or when probe tips must overlap if multiple signals are probed in the same area. I don't know what to tell you about the datasheet availability, but you can check out https://download.tek.com/datasheet/P7500-Series-Datasheet-14.pdf for additional details!