And for the MHL2 and MHF2 series, it indicates the opening/closing stroke.
For details, refer to the "How to Order" section in the web catalog of each series. The parallel type air gripper catalogs can be found here.

The MHF2-X7076A also improves electric contact during tool changes and reduces air leakage due to defective piping connections. Automatic tool changer unit for robots; Bore size: 8mm; Opening/closing stroke (both sides): 16mm; Side piping type; 2 possible mounting types are possible: top mounting (body tapped) and body through-hole

The MHF2-X7076A also improves electric contact during tool changes and reduces air leakage due to defective piping connections. Automatic tool changer unit for robots; Bore size: 8mm; Opening/closing stroke (both sides): 16mm; Side piping type; 2 possible mounting types are possible: top mounting (body tapped) and body through-hole

Finger Stroke: L (Long Stroke), Bore Size: 16mm, Action: D (Double Acting), Finger Material: 1 (Stainless Steel)

Finger Stroke: Standard, Bore Size: 16mm, Action: D (Double Acting), Finger Material: 1 (Stainless Steel)

Bore Size: 16mm, Action: D (Double Acting), Finger Position: 1 (Standard-Side Tapped)

Bore Size: 16mm, Action: D (Double Acting), Finger Option: 1 (Side Tap Mounting)

Bore Size: 16 (16mm), Action: D (Double Acting), Finger Option: 1 (Side Tapped Mounting)

Bore Size: 16mm, Port Thread Type: Nil [M Thread (16mm, 25mm) or Rc Thread (32mm, 50mm)], Body Type: 1 (Adjustable Holding Force Type)

Bore Size: 16mm, Action: Double Acting, Finger Option: Side Tapped Mounting, Auto Switch: -, Lead Wire or Prewired Connector: -, Number: -, Made to Order: -

Bore Size: 16mm, Body Type: Adjustable Holding Force Type, Auto Switch: -, Lead Wire: -, Number: -

How Grip: Pinch, Parallel Type / Open, Parallel Type, Number of Fingers: 2 Pcs., Open Dimension L1(mm): 20.9, Closed Dimension L2(mm): 14.9, Type: [Main Body] Body, Operation Method: Double Acting, Main Body Shape: Square Shape, Gripping Force (Closed Side at 0.5 Mpa)(N): 34, Gripping Force (Open Side at 0.5 Mpa)(N): 45, Environment, Applications: Standard, Additional Function: With Linear

How Grip: Pinch, Parallel Type / Open, Parallel Type, Number of Fingers: 2 Pcs., Open Dimension L1(mm): 170, Closed Dimension L2(mm): 110, Type: [Main Body] Body, Operation Method: Double Acting, Main Body Shape: Square Shape (Wide), Gripping Force (Closed Side at 0.5 Mpa)(N): 45, Gripping Force (Open Side at 0.5 Mpa)(N): 45, Environment, Applications: Dust Resistant, Additional Function:

How Grip: Pinch, Parallel Type / Open, Parallel Type, Number of Fingers: 2 Pcs., Open Dimension L1(mm): 26.9, Closed Dimension L2(mm): 14.9, Type: [Main Body] Body, Operation Method: Double Acting, Main Body Shape: Square Shape, Gripping Force (Closed Side at 0.5 Mpa)(N): 34, Gripping Force (Open Side at 0.5 Mpa)(N): 45, Environment, Applications: Standard, Additional Function: With Linear

How Grip: Pinch, Parallel Type / Open, Parallel Type, Number of Fingers: 2 Pcs., Open Dimension L1(mm): 20.6, Closed Dimension L2(mm): 14.6, Type: [Main Body] Body, Operation Method: Double Acting, Main Body Shape: Square Shape, Gripping Force (Closed Side at 0.5 Mpa)(N): 31, Gripping Force (Open Side at 0.5 Mpa)(N): 36, Environment, Applications: Dust Resistant / Drip-Proof, Additional Function

How Grip: Pinch, Parallel Type / Open, Parallel Type, Number of Fingers: 2 Pcs., Open Dimension L1(mm): 28.6, Closed Dimension L2(mm): 14.6, Type: [Main Body] Body, Operation Method: Double Acting, Main Body Shape: Square Shape, Gripping Force (Closed Side at 0.5 Mpa)(N): 27, Gripping Force (Open Side at 0.5 Mpa)(N): 30, Environment, Applications: Dust Resistant / Drip-Proof, Additional Function

Bore Size: 16mm, Action: D (Double Acting), Finger Option: 1 (Side Tap Mounting), Body Option: Basic Style, Auto Switch: No Switch, Lead Wire or Prewired Connector: 0.5m (Or None in the Case of No Switch), Number: 2 pcs (Or None in the Case of No Switch), Made-to-Order: X7 (Closing Direction Spring Assist)

Finger Stroke: Standard, Bore Size: 16mm, Action: D (Double Acting), Finger Material: 1 (Stainless Steel), Dust Cover: Chloroprene Rubber (CR), Auto Switch: M9N--Solid State, Gen. Purpose, 3 Wire NPN, Horizontal, 0.5M

Finger Stroke: Standard, Bore Size: 16mm, Action: D (Double Acting), Finger Material: 1 (Stainless Steel), Dust Cover: Chloroprene Rubber (CR), Auto Switch: M9N--Solid State, Gen. Purpose, 3 Wire NPN, Horizontal, 0.5M, Lead Wire or Prewired Connector: L (3m), Number: S (1 pc.)

Finger Stroke: Standard, Bore Size: 16mm, Action: D (Double Acting), Finger Material: 1 (Stainless Steel), Dust Cover: Chloroprene Rubber (CR), Auto Switch: M9B--Solid State, Gen. Purpose, 2 Wire, Horizontal, 0.5M