Snap’s latest generation of augmented reality Spectacles have been lambasted by one of the engineers who helped to create them. The glasses, revealed earlier this week, were described as “a disaster” by Sterling Crispin, a former design engineer for Snap.

Snap on Tuesday, September 17, introduced its fifth-generation augmented reality glasses, Spectacles, designed to overlay digital graphics onto the real world. These glasses are currently only accessible to developers who are willing to pay a monthly subscription fee of $99 for a year.