Sheaffer Skrip ink is made by the Sheaffer Pen Company. Amongst fountain pen fans, it is noted for two things: its safeness, and its recent production changes.

Certain inks and certain pens just don't get along well. Some earlier Private Reserve inks, and certain Noodler's speciality inks, for example, have an unfortunate tendency to ruin the nibs, and the short-lived Parker Penman range was infamous for killing non-Parker pens. Skrip, on the other hand, is the canonical 'safe' ink range — even the brighter inks can be used in older and speciality fountain pens without fear of causing damage.

It should be noted that safety is not necessarily a good thing, especially since it usually comes at the expense of having a more vibrant colour — Skrip has been sarcastically compared to writing with Kool-Aid on several occasions.

The production changes occurred in 2002, when manufacturing moved to Slovenia. According to the manufacturer1, the newer ink ranges are less prone to bleeding and feathering, and have an improved bottle and cartridge design. According to detractors, the newer cartridges are far more fragile and harder to insert, and the new range of colours is worthless without the old Peacock Blue and a decent Gold.

Overall, the new range of colours is slightly less limited than the original set, but (as with other manufacturer inks) it is still extremely restrictive when compared to speciality inks from J. Herbin, Diamine and Private Reserve. The selection is as follows:

Blue-Black
A slightly washed out grey-blue colour. Similar to the Waterman colour of the same name.
Blue
A moderately bright medium blue. Not as vibrant as the medium blue styles from many manufacturers.
Black
Murky grey, on par with the older Diamine black and nowhere near as dark as J. Herbin Perle Noir or the new Diamine Quartz Black.
Red
A surprisingly good bright red. This is one of the few definite improvements over the old range of colours.
Green
Somewhere between green and blue.
Brown
A 'milk chocolate' brown.
Turquoise
Supposedly a replacement for the old Peacock Blue, but considered by many to be lacking strength.
Purple
A violet purple.
Orange (cartridge only)
Washed out, thin, and sadly lacking when compared to Diamine's offering.
Pink (cartridge only)
A medium pink colour, similar to the original Diamine pink.
Gold (cartridge only)
A bright yellow, similar in shade to the J. Herbin Bouton d'Or and equally difficult to use in anything other than broad nibbed pens.

It should be noted that Sheaffer cartridges are not in either international size. Rather, they are a proprietary format that will only fit in newer Sheaffer pens. The bottled ink, which comes in a 50ml frustum-shaped bottle, is not tied to the manufacturer's pens.

Sheaffer ink is considerably easier to find than those from speciality manufacturers. It is available in many stationers and most pen shops.

1: http://www.pendemonium.com/sheaffer_faq.htm