Belkin's product page states that the screen protector is now 0.29mm thick, compared to 0.21mm for the original InvisiGlass Ultra. As such, the new version will hopefully prove to be more durable, after dozens of customers complained about the first iteration cracking way too easily during normal day-to-day usage.
Belkin halted sales of the original InvisiGlass Ultra in late December due to a wave of negative feedback, including several one-star customer reviews. At the time, a company spokesperson told MacRumors that it considers "product quality and consumer feedback" to be of "paramount importance."
"We have been constantly testing this product since we released the first generation of it timed to iPhone X availability and things have evolved since you and I last spoke," a Belkin spokesperson informed MacRumors. "We identified some improvements to be made in the next generation of this product."
Apple and Belkin appear to have been providing refunds to customers who purchased the original InvisiGlass Ultra and found it to be defective, so we recommend contacting the companies if your screen protector easily cracked.
The new InvisiGlass Ultra remains $39.95 from Apple. The updated screen protector is still listed as "coming soon" on Belkin's website.