This is an opencart extension that was built for better flexibility and customization. You can define how you want the shipping module work with your requirement.
You can use this extension for:
1) overseas shipping that do/don't have a fixed rate for shipping (use option 'Exclude Country' to deselect your country)
2) pre order that do not charge shipping on the checkout but need to tell the customer some information that is important. For example ask customer to redeem the coupon at a website link.
3) can change shipping name easily form the 'Custom Shipping' option backend