abbreviations used in explaining thread patterns:
M=Metric (M16X1 means these numbers are metric instead of standard)
LH=Left Hand (M16X1 LH means the thread pattern is backwards and threads on the opposite direction)
RH=Right Hand (M16X1 RH means the thread pattern should be the same as usually expected)
TPI=Threads Per Inch
M16 x 1 LH to .578"-28 TPI Conversion Adapter
Factory Direct $21.95
This adapter will allow you to mount most any suppressor or muzzle accessory using .578"-28 U.S. standard threading onto the Heckler & Koch USP 45 caliber and other handguns with the 16MM X 1 left hand barrel threading.
M16 x 1 LH to 5/8"-24 TPI Conversion Adapter
Factory Direct $21.95
This adapter will allow you to mount most suppressor's or muzzle accessory using 5/8"-24 U.S. standard threading onto the Heckler & Koch USP 45 caliber and other handguns with the 16MM X 1 left hand barrel threading. 
M16 X 1 LEFT HAND
.750" O.D. x .570" OAL
H&K USP series 45 caliber
Factory Direct $11.95
M16 X 1 Right HAND
.812" O.D. x .625" OAL
Factory Direct To You Price $11.95
M14.5-1 LH to 9/16"-24
Conversion Adapter
FACTORY DIRECT TO YOU PRICE $21.95
M14.5-1 LH to 16mm x 1 LH
Conversion Adapter
FACTORY DIRECT TO YOU PRICE $21.95
M16 x 1 LH to M18 x 1 RH Conversion Adapter
Factory Direct $21.95
This adapter will allow you to mount most suppressor's or muzzle accessory using 5/8"-24 U.S. standard threading onto the Heckler & Koch USP 45 caliber and other handguns with the 16MM X 1 left hand barrel threading. 
M16 X 1 Right HAND
.812" O.D. x .625" OAL
Factory Direct To You Price $11.95