ProFlow CamLock Couplers
Stainless Steel - Brass - Aluminum - Polypropylene 1/2" to 6" available
The ONLY fitting that fits in a USPS Small Flat Rate Box is 1/2"
For any other size, choose "general" Priority Mail or UPS
We always refund any excess shipping cost, so "overbuy" your box so your shipment is not voided or delayed.