To enable this, create a smart collection named All Products and set the condition to 'Product price is greater than 0'. You can create a collection through the 'Collections' menu in Shopify admin. Or you can turn this section off through theme settings.
Manifold Sizes: 7” Cylinder centres (177mm - 193mm)
Band Sizes: 185mm centres
Cylinder Diameter & Size: 171mm (10L, 12L)