MSK-146BL - The MSK-146BL-4 20" long arm machine is designed to run at speeds up to 2,500 rpm. This makes it suitable for sewing applications where productivity and flexibility is important. Flexibility and performance. The ability of the MSK-146BL to handle a wide variety of sewing tasks makes it a very flexible machine for any sewing environment where a zig-zag stitch is required for heavier material. All of the convenience features are standard to make your job easier; and of course our trusted reputation for building quality, long lasting equipment.