Description The Sumart Universal Bleed Block allows you to easily bleed your 2-piston & 4-piston hydraulic brakes. This bleed block tool works better than a screwdriver! Don’t risk damaging your pistons, simply insert this little tool into your caliper and twist the knob to safely spread your pistons. Sumart Universal Bleed Block Specs Designed to prevent damage to ceramic pistons during maintenance Options for 2-piston (UBB-20) & 4-piston (UBB-40) brakes Compatible with many hydraulic brake systems Can be easily tightened or loosened by hand 3mm Allen key can be used if needed