Manufacturer Specifications
RIDGID lists a “2.5 in. Dust Port” for both models. This lets the Finder classify a 2-1/2 in. setup as a nominal direct match while retaining a warning about actual ID/OD.
Which Hose Should You Use?
A 2-1/2 in. hose is the logical starting point when its cuff is designed to mate with a 2-1/2 in. tool port. Smaller hoses such as 1-7/8 in. or 1-1/4 in. require an appropriate reducer or adapter.
RIDGID also sells 1-7/8 in. hoses with adapters for certain 2-1/2 in. interfaces. This illustrates why hose diameter and cuff size should not be treated as the same dimension.
Reducers and Airflow
A smaller reducer may solve the connection problem but reduces available cross-sectional area. For a miter saw, keep the connection as large, short and well-sealed as your vacuum allows.
Frequently Asked Questions
What size dust port does the RIDGID R4113 have?
RIDGID specifies a 2.5 in. dust port.
Does the R4123 also use a 2.5 in. port?
Yes. RIDGID also specifies a 2.5 in. dust port for the R4123.
Can a 1-7/8 in. hose be used?
Yes, with an appropriate adapter, but do not assume direct fit from nominal size alone.
Technical Sources
The sizes and part references in this guide are based on the following official pages: RIDGID R4113 RIDGID R4123.
Disconnect the machine before measuring or installing a fitting. Check the manufacturer manual, keep guards in place and never force a connector whose geometry does not match.