The RK 520MXU is the lightest sealed-ring enduro/motocross chain available in market today, 13.8g/link, only 0.1g/link heavier than RK 520MXZ4 non sealed chain
 
The MXU chain series is the next generation of enduro/motocross racing chains featuring the RK patented technology of Ultra Thin UW-Rings, which make it possible to design a Sealed Chain with the weight of a Non-Sealed Chain.
 
UW Seal Rings stop debris and dirt entering the chain rollers which ensures efficient horsepower transmission from the engine to the rear wheel throughout the chain life
 
For Enduro & Motocross
RK UW Seal Ring
Lightest off-road seal chain 
Use by Graham Jarvis
Use by Top MXGP teams
Colour:
Gold
Grade:
Narrow Pitch Enduro
Length:
118
Pitch:
520
Sealed:
Yes
Type:
MXU
Tensile Strength (Lbs):
8005
Tensile Strength (N):
35.6
Fitment Summary
Compatible with 107 models (yearly).
Barossa: Baja 170, Cheetah 170, Magna 170
GasGas: ECF 2504T, EXF 350 Cross Country
Husaberg: FE 2504T, FE 3504T, FE 3904T
Husqvarna: FE 2504T, FE 3504T, FE 350S
Kawasaki: KDX 250C1, KDX 250C2, KDX 250C3
KTM: EXC 150 Enduro, EXC 250 Enduro, EXC 300 Enduro, EXC 350 Enduro, EXCF 250 Enduro, EXCF 250 six days, XCF 350, XCFW 250, XCFW 2504T, XCFW 350 six days, XCW 250, XCW 250TPI
TM Racing: SMR 660Fi, SMX 660Fi