User blog comment:Prismwolf/Best Upcoming MARVEL Film: Avengers vs. X-Men vs. Guardians of the Galaxy/@comment-1713281-20131001143346/@comment-3317214-20131004025807

However, there's a few things that suggest that they won't be the only sentinels we see.

We know that the sentinels we've seen in promotions are Mark I sentinels, that were produced since 1973. We also know that in 2023, they're celebrating 50 years of achievement, halting production of the Mark I to shift their efforts to manufacturing the Mark X sentinels, which are described as their "first complete overhaul of the Sentinel line".

All of the information is at the Trask Industries website.