What did Apple mean when it said it changed materials to improve the keyboard on 2019 MacBook Pros? You should now have a better idea. iFixit has torn down the laptop to reveal at least a pair of changes to the butterfly mechanism that might affect reliability. To start, the switch cover now appears to be made from polyamide (aka nylon) instead of polyacetylene -- it's not certain just how this improves the situation, but it's a conspicuous change. There also seem to be changes to the metal dome switch, possibly involving either a new alloy or heat treatment. The added resilience could prevent the switches from breaking or deforming due to wear and tear, heat or other common culprits.