This is a multi fitting dip stick to take all readings from the 722.6 transmission range.
RED Handle

The tool is designed for checking ATF level.

Models: Mercedes 1997 and NEWER with 722.6 transmissions with no dip stick. Also Suits 724, 5 speed 7G DCT 

OEM: 140 589 15 21 00 / 140589152100

Note:
Transmission Codes 722.3 & 722.4 have their own dipstick so it is a spare part not a tool. 
If you need a dip stick for these please call Mercedes.