Scorpion 1000/1001 4X4 SVS brake system. The basic of the system is that you can change the brake force, by changing the number of brake blocks engaged by external dial. As spool has 6 blocks, the total setting available is from 0 to 6. Also you may change the number of blocks engaging by locking front row blocks manually. The number of front row blocks pulled to activate decides the initial setting # of Min. And each notch of dial adds another blocks engaged. And, the Max adds 3 blocks engaged to the initial #. If you pull out 1 of three front row blocks, you may change the setting from 1-4 by dial. If you pull 3 of them out, your setting is between 3-6 by dial. The blocks in rear row may not turn on/off. This 4x4 system is only to Shimano Japan models, and no export model like Chronarch MG50, Curado has the system.