my guess is this- the titleist staff can see what ball you say that you play on your profile, so they send you a sleeve of test pro v1/x depending on what you said. for example, on my profile i said that i play pro v1xs, and in the mail, i recieved a ball with a red number. may be a coincidence, but who knows.

I just tested the same ball yesterday and it feels and is durable like a v1x off the tee but the spins and feels like a v1 with middle irons in.  Dimple pattern was a 1x, spun like heck with a 60 from 50 in.

Interesting.. I got balls for a survey and they said test and had a black number.. I believe the black is the prov1 and the red is the x. 

I also received the red number sleeve. Thought was a really good responsive ball, great around greens! Not sure if ProV1x like everyone thinks, but regardless, great ball and hopefully we will be told so I can go buy some more! Friend is scratch player and he murdered it a couple of drives! Wanted to but the sleeve from me!!!!  LOL  Didnt do it! Liked them too much myself!

I agree. This ball was even longer then the ProVx I currently play. I played on a windy and cold day and it was incredible!! Would switch to this ball for sure!

I showed to my pro and he said it was a Pro V1