A monetary value above (or at) which the shipping rate becomes free. Intended to be used via an <a class="localLink" href="/OfferShippingDetails">OfferShippingDetails</a> with <a class="localLink" href="/shippingSettingsLink">shippingSettingsLink</a> matching this <a class="localLink" href="/ShippingRateSettings">ShippingRateSettings</a>.