Original specs/details

Full Name IBM Space Saver Numeric Keypad
Part NumberPart Number
The number used to describe this keyboard's specific release; usually specific for a target region, language or SKU, etc.
A designation from my own type naming scheme used to categorise this keyboard with or from others by their common features and market intent but may/may not be derived from official names.
Model M4-1 Space Saver Numeric Keypad
The name of the known switching mechanism that lies under this keyboard's keys.
IBM buckling rubber sleeves (M3/M4 rod-actuated type)
The style of this keyboard's flip-out or extendable feet. If applicable, this may also state how many levels of height adjustment are available and whether the feet could be rubberised.
Rubberised single-setting flip-out feet
The keyboard-to-host connection. This is could be a description of a cable (its colour, whether its coiled, whether its detachable, and what connector is at its end) or the name of a wireless technology.
Detachable modular-10P10C ("RJ-50") to modular-10P10C ("RJ-50") cable
Form FactorForm Factor
The standardised or universally acknowledged name for this keyboard's layout form factor.
Production Date 1995-03-08
Acquisition Date 2020-07-02

About this keyboard type

The IBM Model M4-1 Space Saver Numeric Keypad was the complimentary numeric keyboard option available for pairing with Model M4-1 keyboards. It features the same assembly design as the Model M3 numeric keypad, however, the case is enlarged to match the design of the host keyboard and various layout variations exist - most commonly, an extra "00" key is added at the expense of reducing the "0/Ins" key to a single key-unit size. Without modification, these keypads can only be used when coupled to an M4-1 (or M4) host keyboard via a modular 10P10C ("RJ-50"-like) cable. The only real difference between this M4-1 version and the M4 version is purely the sticker on the back.