Compared to the ZSE20, the ZSE20AF adds a 2nd switch output, as well as an analog output, either voltage or current.  ZSE20A is vacuum rated, while the ZSE20AF is rated for vacuum and a low positive pressure range.  Each model in the ZSE20 family offers a 2-screen, 3-color display.  The main screen shows the current measured numeric value in orange. 

Body Size: 200 (AC20), Style: T-Shaped Piping Adapter, Thread Type: Rc, Port Size: 01 (1/8)

Size: 1 (Body Ported), Operation: 0 (Air Operated Style), Port Size: 01 (1/8), Thread: T (NPTF)

Size: 22 (Base Mounted), Operation: 0 (Air Operated Style), Port Size: 01 (1/8), Thread: T (NPTF)

Body Size: 20, Thread: Rc, Port: 01 (1/8), Option: CG (C + G), Attachment: T (T Spacer), Semi-Standard 1: 2 (Metal Bowl), Semi-Standard 2: R (Flow Direction: Right->Left)

Body Size: 20, Thread: Rc, Port: 01 (1/8), Option: G (Round Pressure Gauge w/Limit Indicator), Attachment: T (T Spacer), Semi-Standard 1: 2 (Metal Bowl), Semi-Standard 2: Standard

Body Size: 20, Thread: Rc, Port: 01 (1/8), Option: CG (C + G), Attachment: T (T-spacer), Semi-Standard 1: 2 (Metal Bowl), Semi-Standard 2: R (Flow Direction: Right->Left)

Body Size: 200 (AC20), Style: T-Shaped Piping Adapter, Thread Type: N (NPT), Port Size: 01 (1/8)

Body Size: 300 (AC30), Style: T-Shaped Piping Adapter, Thread Type: N (NPT), Port Size: 01 (1/8)

Model: 01 (Single Acting), Thread: N (NPT), Accessory: None, Suffix: T [High Temperature (-5 to 100 °C)]

Size: 01 (Size 01), Passage Symbol: FG (2 Position Double), Number of Solenoids: S (Single), Rated Voltage: 3 (24 VDC), Light/Surge Voltage Suppressor: None, Sealing Type: Metal Seal, Port Size: A02 (Side Ported, 1/4), Thread: T (NPTF)

Body Size: 20, Thread: Rc: Size 20, 25, 30, 40; M5: Size 10, Port Size: 01 (1/8), Option: Standard, Attachment: T (T-Interface), Semi-Standard 1: Standard, Semi-Standard 2: Standard

Size: 01 (Size 01), Passage Symbol: FG (2 Position Double), Number of Solenoids: S (Single), Rated Voltage: 3 (24 VDC), Light/Surge Voltage Suppressor: None, Sealing Type: R (Rubber Seal), Port Size: A02 (Side Ported, 1/4), Thread: T (NPTF)

Solenoid Direction: Opposite side of A port (A port bottom ported for Type 40), Type: 42 (A Port Side Ported; 42S: Solenoids on the Same Side of A Port), Stations: 01, Port Size: 01 (Rc 1/8), Thread: T (NPTF)

Model: 01 (Single Acting), Thread: N (NPT), Accessory: B (Bracket), Suffix: T [High Temperature (-5 to 100 °C)]

Function: 1 (2 Position Single), Body Option: 1, Piping: 0 (Side), Port Size: 01 (1/8), Voltage: 5 (24VDC), Electrical Entry: T (Conduit Terminal), Option: P (Manual Override, w/Lock), Thread: T (NPTF)

Series: 3 (VFA3000), Actuation: 1 (2 Position Single), Body: 30, A, B Port Size: 01 (1/8), Thread: T (NPTF)

Series: 1 (VFA1000), Actuation: 1 (2 Position Single), Body: 20, A, B Port Size: 01 (1/8), Thread: T (NPTF)

Series: 1 (VFA1000), Actuation: 2 (2 Position Double), Body: 20, A, B Port Size: 01 (1/8), Thread: T (NPTF)

Size: B (Base Mounted), Operation: 3 (Manual Handle Style), Sealant: Nitrile Rubber, Port Size: 01 (1/8), Thread: T (NPTF)