Pick the AFT11 Series coupler that matches the port sizes you want to interface.

Item 1	Dimensions	Item 2	Dimensions	BIOPAC Coupler
15 mm	OD	22 mm	ID	AFT11B
20 mm	OD	22 mm	ID	AFT11B
22 mm	ID	15 mm 20 mm 22 mm	OD OD ID	AFT11B AFT11B AFT11B
22 mm	OD	22 mm 25 mm	OD ID	AFT11C AFT11C
22-25 mm	OD	22-25 mm 35-38 mm	OD ID	AFT11E AFT11E
25 mm	ID	25 mm	ID	AFT11C
25-30 mm	OD	25-30 mm 28-35 mm	OD ID	AFT11A AFT11A
28-35 mm	ID	25-30 mm 35 mm	OD ID	AFT11A AFT11A
34-37 mm	ID	41-47 mm	ID	AFT11F
35 mm	ID	28-35 mm 38 mm	ID ID	AFT11A AFT11E
35-38 mm	ID	22-25 mm	OD	AFT11E
35-38 mm	OD	35-38 mm	OD	AFT11D
35 mm	OD	28.6 mm	OD	AFT11H