749 equipment max checkout

Resolves #749
here's the trace:
```
app/views/equipment_models/_form.html.erb:12:in `block in _app_views_equipment_models__form_html_erb___1671969997400540714_70014930452620'
app/views/equipment_models/_form.html.erb:1:in `_app_views_equipment_models__form_html_erb___1671969997400540714_70014930452620'
app/views/equipment_models/edit.html.erb:3:in `_app_views_equipment_models_edit_html_erb___3156120513192557427_70014930401300'
```