The Brow Tool is engineered to fit Slim Retractable Eyebrow Pencils. Check out the list...

ANASTASIA BROW WIZ
BENEFIT PRECISELY MY BROW
BOBBI BROWN MICRO BROW
CHARLOTTE TILBURY BROW CHEAT
CHRISTIAN DIOR DIORSHOW BROW STYLER 
CLINIQUE QUICKLINER FOR BROWS
COVERGIRL ULTRAFINE BROW PENCIL
ELF ULTRA FINE BROW PENCIL
ESSENCE FINE BROW PENCIL 
GIORGIO ARMANI HIGH PRECISION BROW PENCIL
GUCCI STYLO À SOURCILS
HAUS LABS THE EDGE PRECISION EYE PENCIL,
HOUR GLASS ARCH BROW MICRO SCULPTING PENCIL 
ITCOSMETICS BROW POWER MICRO EYEBROW PENCIL
KEVYN AUCOIN PRECISION BROW PENCIL
KYLIE BROW PENCIL
LANCÔME BROW DEFINE PRECISION BROW PENCIL
L'ORÉAL BROW STYLIST DEFINER
MAC EYE BROWS STYLER
MAKE UP FOR EVER AQUA RESIST BROW DEFINER
MAYBELLINE ULTRA SLIM DEFINING EYEBROW PENCIL 
NARS BROW PERFECTOR
NYX MICRO BROW PENCIL
ONE/SIZE BROWKIKI MICRO BROW PENCIL
REFY BROW PENCIL
RIMMEL BROW PRO MICRO
SEPHORA COLLECTION RETRACTABLE BROW PENCIL
SMASHBOX BROW TECH MATTE PENCIL
TARTE AMAZONIAN CLAY WATERPROOF BROW PENCIL
TOO FACED SUPER FINE BROW DETAILER
TRISH McEVOY PRECISION BROW SHAPER 
URBAN DECAY BROW BEATER