The leaflet in .pdf here:

http://www.libertytest.com/assetmanager/uploaded/pdf-200866-84927-3457a.pdf

Operating Manual here :

https://www.manualslib.com/manual/1004584/Hp-3457a.html

HP 3457A 3 1/2 to 61 /2 Digit DMM with Extended Resolution to 71 /2 Digits

• Over 1350 Readings/sec at 3 1/2 Digits
• Seven Functions—DCV, ACV, DCI, ACI, Ohms, Frequency and Period
• Three Plug-in Multiplexer Options
• DC Sensitivity to 10 Nanovolts
• Size: 89 mm H (without removable feet) x 425mm W x 292mm D (3.5" x 16.75" x 11.5"). Height (with removable feet): 100 mm (4"). Allow 76mm (3") additional depth for wiring
• Net Weight: 5.05 kg (11.1 lbs)

The HP 3457A has seven functions with 3'/2 to 6'/2 digits of resolution extendable to 7'/z digits at reading rates from 1 reading every 2 seconds to 1350 rds/s and basic DC volts accuracy as good as 5 ppm. In addition, the input of the HP 3457A can be expanded up to ten channels with either of the optional plug-in multiplexer assemblies. On the bench, the front panel operation is extremely flexible and comprehensive.  In systems, the Hewlett-Packard Interface Bus (HP-IB) is standard.