From Marcrist
Dust Extraction Unit 1¼" UNC (M) for all combi diamond core dry and wet 1¼" UNC (M) bitsFeatures & Benefits High quality Long lasting 1/2" BSP Female & 1.1/4" Male Connections Taper cacuum connector, suits most units Proven reliable Marcrist technology High performace for the home or tradesman Warranty: 1 year