Shimano Disc Brake Caliper Bleeding Spacers. Also known as a bleed block. This is exactly what you need to bleed your Shimano brakes. This little block sits between the piston during the bleed to get the accurate amount of fluid into your system. Works with BR-M4050, BR-M446, BR-M395, BR-M396 brakes.Useful for retaining the pistons in the correct position when pads are removed from the caliper for bleeding Shimano Bleeding Spacer Brake Tool UPC: 689228299641