What size vise is this?

[Wamsutta]

Mower Medic 1 video. He's getting ready to press some bearings into a string trimmer fan housing.

How big is that vise? Are vises sized by jaw width?

 

[The Cobbler]

I'd say 4 or 5"
they are measured by jaw width, which to me doesn't seem to make sense

 

[Wamsutta]

I'd say 4 or 5"
they are measured by jaw width, which to me doesn't seem to make sense

You would think they'd be measured by capacity like a bar clamp.

 

[General Geoff]

The most typical bench vise size measurement is by jaw width, but that's kind of like defining trucks by wheelbase and nothing else. So many other factors like throat depth, opening capacity, overall mass, material, tensile strength, main screw thread pitch, maximum clamping force, etc.

The Wilton in the OP photo, looks to me like an older 400S

 

[neophyte]

I'd say 4 or 5"
they are measured by jaw width, which to me doesn't seem to make sense

Leg Vises, or the similar type of vise without the leg, were the standard “Blacksmith’s Vise” for centuries, if not a millennia or longer.
The typical Leg vise is limited in how wide the jaws will open, so there was limited use in classifying that style of vise by the jaw opening, especially since the jaws tended to unscrew with a single pivot point below, making the jaws less parallel and potentially less useful the wider the jaws were opened.
A common technique used with those older vises, however, was to clamp sheet metal in those leg vises, and then to hammer a cold chisel across the vise jaw surface, to cut the sheet metal.
This may be why the vises used to be classified by jaw width, rather than opening, with the classification system sticking even after the “modern” style of bench vise made from cast iron started to become common.

 

[Shiftless]

Looks like 4 inch to me too.
Poor old bullet has been abused in the past. Look at the broken off jaw support shelf.

BTW, a vise is not a press. Lots of perfectly good vises have been ruined by such tasks. Not bad for light weight duty but if you need to apply lots of force by using a cheater pipe or beating on the handle with a hammer, something just might break.