15mm Rod Riser System
The  RailBlock has 4 Types of Thread: 1/4", 3/8", M4 & M5 thread.4 Types of Thread: 1/4", 3/8", M4 & M5 thread.1/4" thread: thread diameter is international standard 1/4";3/8" thread: thread diameter is international standard 3/8";M4 thread: thread diameter is 4mm;M5 thread: thread diameter is 5mm.The railblock Rod Clamp can be mounted on any standard 15mm rods on DSLR Rig,Rails center-to-center distance : 60mm.Package Included:1 X Rod clamp