Standard cleaning rods use 8-32 thread, but .17 and .20 caliber brushes, jags, and mops use the smaller 5-40 thread. Without this brass cleaning rod adapter, you need a separate rod just for your smallest rifles. Thread this adapter onto your existing 8-32 rod and every 5-40 accessory fits instantly - no second rod, no hunting for specialty equipment.
The .17 HMR and .17 WSM have become popular varmint and target calibers, but their cleaning accessories use the thinner 5-40 thread because the standard 8-32 is physically too large for that bore size. Most shooters discover this mismatch the day their new .17 cal brush arrives and won't screw onto their cleaning rod. This thread adapter is the fix. Solid brass construction protects both thread types from cross-threading damage and resists the solvents and oils that are part of every gun cleaning session.
Small enough to live permanently on your .17 cal brush set or tossed in the bottom of your cleaning kit. Either way, this cleaning rod adapter means your 8-32 rod handles everything from .17 caliber up - one rod for every rifle and pistol you own.