I have a 4 gallon wet/dry handheld vacuum - model number 125.12002 - and it fits perfectly. Fits just like the old filter and seems to work even better! I often make a drywall degreaser, and even with a dust substitute attached to my hose, the filter still clogs very easily. Very glad I can wash and reuse it - it will last a lot longer! It's important to keep the air as clean as possible, so I'm glad I have the bonus of a HEPA filter. With this filter, the vacuum cleaner works as it should. Very satisfied and to be recommended!