heel cup - / hiːl kʌp / -
noun
The rear part of an alpine or hybrid ski binding that locks around the heel of an alpine ski boot to secure the boot into the binding. The fit between the heel cup and boot heel lug is governed by a International Standards to ensure compatibility between brands. The ISO 5355 standard covers alpine boots / bindings and the ISO 9523 covers touring boots /bindings.
\\ You might want to check your forward pressure settings as it doesn't look like you're getting a good fit into that heel cup.
