Ball-bearing washer compatibility varies by model and production run.
Known compatible flipper models (some variations only) include, but are not limited to:

A-100 Flipper (Tanto and Spearpoint)
Sheepdog (Spearpoint and Bowie)
Mini Sheepdog (Spearpoint and Bowie)
Mini CQC-7 Flipper 
CQC-7 Flipper (ball bearing version only)
Karambit Flipper (ball bearing version only)
CQC-8 Flipper (ball bearing version only)
Horseman Flipper (ball bearing version only)
Headless Horseman Flipper (ball bearing version only)
Some XHD Flipper Knives (ball bearing versions only)
MX-200 (ball bearing version only)
Balisongs
Huck Flipper 
Mustang Flipper
Battalion
Sig Legion 
Roughneck

Please note: Emerson has produced multiple versions of many models over the years, and not all variations of the models listed above use ball-bearing washers. If you’re unsure what your knife uses, email us with clear photos of the pivot (both sides) and any markings/date code, and we’ll help confirm compatibility.