A permanent magnet-based magnetorheological fluid clutch (MRF) with a novel field blocking mechanism for torque adjustment is presented in this article. Magnetostatic simulations were used to optimize the design of the MRF clutch so as to increase its performance. A magnetic flux density measurement setup was used to confirm the correctness of the magnetostatic simulations. https://parisnaturalfoodes.shop/product-category/hair-force-2/