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.

Auto switches can be integrally mounted.Wide opening air gripper, Parallel style, Applicable bore size: 10, 16, 20, 25, 32, 40 mm, Opening/closing stroke range: 20-200 mm, Auto switch capable, MHL2 Gripper, GRIPPER, C24, 1.08 lb

PISTON ASSY, MHL2-40*

Auto switches can be integrally mounted.Wide opening air gripper, Parallel style, Applicable bore size: 10, 16, 20, 25, 32, 40 mm, Opening/closing stroke range: 20-200 mm, Auto switch capable, MHL2 Gripper, GRIPPER, C24

Auto switches can be integrally mounted.Wide opening air gripper, Parallel style, Applicable bore size: 10, 16, 20, 25, 32, 40 mm, Opening/closing stroke range: 20-200 mm, Auto switch capable, MHL2 Gripper, GRIPPER, C24, 5.23000 lb

Part Number Description: SEAL KIT (MHL2-40)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: M1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

RACK ASSY, MHL2-40*

Part Number Description: PISTON ASSY (MHL2-10D1)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: E1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PISTON ASSEMBLY (MHL2-16D1)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: G1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: RACK ASSEMBLY B (MHL2-20D)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: G1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PISTON ASSY (MHL2-20)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: H1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: RACK ASSY (MHL2-20)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: H1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PINION ASSEMBLY (MHL2-20D2-4)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: H1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: ASSY PISTON (MHL2-25)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: I1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PISTON ASSY (MHL2-25D1)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: E1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: RACK ASSY (MHL2-25D1)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: E1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: RACK ASSY (MHL2-25D2)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: E1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: ROD COVER FOR MHL2-25D   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: I2   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PISTON ASSY FOR MHL2-32D   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: H1   Part Code: 2   Reference Code:  J   PDF Documentation: PDF   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number

Part Number Description: PINION (MHL2)   Product Line: A   Product Line Description: ACTUATOR   Family Code: 509   Family Description: MHL GRIPPERS   Class Code: G1   Part Code: 2   Reference Code:  J   This is a custom made item that is NOT returnableClick here to report information errorImage shown may not match exact part number