The Four Square was a relatively short-lived, rather over-designed mechanical pencil, hence its relative rarity.  It used square leads and this version - before they went to the rather bulky ergonomic grip design - is the most eye-catching.  It lasted from around 1935 - 1936.  It has two significant features:

1.  A square barrel with one transparent face showing the internal mechanism.  Inside, it has a red dot in the lead propelling mechanism visible to the user.  This red dot is aligned with the end of the piece of lead in the barrel - giving you an indication of how much lead is left.

2.  A fantastically designed cap.  Unscrew it to access the lead storage chamber.  Screw it back on and pull the cap bushing off.  Then reverse the cap bushing - and push it back on - this pushes out the eraser.  Talk about interactive.

This was a relatively entry-level priced pencil - but its design was not entry level and so production was not cheap.  The Four Square was outmanoeuvred by cheaper models which did the same things much more simply.  The Four Square lasted only about 6 years in 3 versions before disappearing.  This is the "middle" years version.

Four Square pencils did not appear in Wahl catalogues of the time - so the only history I can find of its advertising is shown in my photographs (an advert from 1935).  It does seem to be a bit of a specialist collectors' item.

This pencil is a single unit, square-faced barrel of black plastic, with the white chevron swoops embedded in the plastic (not surface printed).  The plastic is in very good condition - no cracks, damage, gouges etc.  There is age-related handling wear and micro scratches visible under magnification.  The metal clip has some slight brassing (see photograph) and is stamped "EVERSHARP" and "MADE IN U.S.A.".  The lead cone has 3 chased lines of finger-grip (it is the cone which is turned to propel / repel the lead).

The cap is in metal painted black and is in good condition, not dented, some wear.  The top of the cap has a metal disc.  It unscrews cleanly from the barrel on a clean aluminium post, to reveal the lead storage chamber.  Screwed back on, the metal bushing can then be pulled off the aluminium post, the cap is then flipped round and replaced "upside down".  When pushed home the eraser is propelled out.  The original eraser is in situ, appears completely unused (if rather hard).

A non-original copy of the instructions is included.

A canister of vintage Wahl Eversharp Square Leads is also included - it is unusual because it is a gold-coloured case (usually they are a silvery metal) with the standard red top cap.  There are lots of original square leads inside, to keep the pencil going for ages.  The canister is stamped "H.B MED. SOFT" and are described as "SQUARE LEADS" on the other side. 

This pencil will be sent in a protective velvet pouch.

Dimensions (approximate):  15.2cm long (eraser covered), 15.6cm (eraser exposed), 0.8cm wide, 15.2g

I will send this lovely bundle carefully packed via signed-for Royal Mail, and please note if you are buying from outside the UK, this pencil will be delivered by the eBay Global Shipping Programme (GSP) which will take around 10 days to get to you.