{%- macro connection_spec(ap) -%}
  {%- if ap.iso_thread -%}
    M{{ ap.iso_thread.diameter_mm }}×{{ ap.iso_thread.pitch_mm }}
  {%- elif ap.unc_thread -%}
    {{ ap.unc_thread.diameter_fraction }}-{{ ap.unc_thread.tpi }} {{ ap.unc_thread.series.value }}
  {%- elif ap.clamp_connection -%}
    {%- if ap.clamp_connection.min_mm is not none -%}
      {{ ap.clamp_connection.min_mm }}–{{ ap.clamp_connection.max_mm }} mm
    {%- else -%}
      {{ ap.clamp_connection.min_in }}–{{ ap.clamp_connection.max_in }} in
    {%- endif -%}
  {%- elif ap.static_connection -%}
    {{ ap.static_connection.od_mm }} mm OD
  {%- else -%}
    —
  {%- endif -%}
{%- endmacro -%}