The limited availability of the Apple Watch at launch is the result of supply constraints related to the taptic feedback sensors, the Wall Street Journal reports. The component, which provides the wrist-based vibration feedback, was being manufactured by two suppliers, one of which was found to be producing faulty components. The problem apparently remained undiscovered until mass production began in February, only revealing itself through reliability testing on finished units coming off the assembly line. Some completed watches were apparently scrapped entirely as a result, and Apple was forced to move all of its production to a single supplier, which has not been able to scale up production as quickly as needed to meet the demand for the new wearable device. While it’s unclear how much the taptic engine component problems altered Apple’s retail availability plans overall, several other component suppliers have reported that they have been told to slow down production until June, in line with prior retail availability announcements and shipping estimates that have been coming out of Apple.