UPS API Package Types

Package Type ID
UPS Letter 10
Customer Package 11
UPS Tube 12
UPS Pak 13
UPS Express Box 14
UPS 25 KG Box® 15
UPS 10 KG Box® 16
Pallet 145
Small Express Box 513
Medium Express Box 514
Large Express Box 515
Flats662
Parcels663
BPM664
First Class665
Priority666
Machinables667
Irregulars668
Parcel Post669
BPM Parcel670
Media Mail671
BPM Flat672
Standard Flat673

See full UPS API (CarrierID=3) Reference.