Which service do you choose? My suggestion is either UPS or Fed Ex for several reasons. First and foremost is the quality tracking services. You can follow the delivery right to the destination plus have a delivery receipt showing when it was delivered and who signed for it. USPS offers very good service, but based on past experience, personally, I most comfortable with either UPS or Fed Ex.
Best practices for shipping a VNG or caloric irrigator
How to Pack Your Difra VNG Device
We recommend you keep the molded plastic Difra travel case in which your VNG was shipped to you. This offers the best protection for shipping your VNG. The internal space is tailored to the VNG mask and other components allowing them to well protected during shipping. I highly recommend putting the mask in the Difra case with any other components we request, then put the Difra travel case in a sturdy cardboard box with shipping padding for the safest, most effective way to ship without damage.
If you cannot locate your Difra travel case, then you will need a sturdy cardboard box large enough to contain the mask and other components. Wrap the goggles heavily in bubble wrapping, not peanuts.
With a NysStar II, the binocular mask you need to be certain the molded eye cover is installed and secured. This helps protect the glass mirror. You do not want this mirror to get broken since your replacement cost is $1,000. Wrap the entire mask with bubble wrap. It's best not to skimp on the bubble wrapping to make sure we receive your VNG without further damage. All of your other components need to be wrapped as well. Fill in any space in the box with shipping material, securely tape the box shut with shipping tape and now you are ready to ship your device.