The Milwaukee MI0021 are plastic 25 mL beakers for sample testing and preparation. Set of four per package. The peristaltic tubing for the Mi455 and Mi456 mini titrators stretches over time. This stretching eventually results in a failed calibration. This is resolves by replacing the tubing as part of the mini titrator's maintenance process. The MX includes the tubing, fittings, titrant bottle cap and a dosing tip. The tube set allows for the connection between titrant bottle and sample beaker. Design Features Includes titrant bottle cap, fittings and dosing tip Fine dispensing tip for accurate dosing Replacement tubing for when old tubing is greater than 6.5 cm (2.5 in)standardized solution. The Milwaukee MI0020 are plastic 50 mL Beakers for sample testing and preparation. Set of four per package.