“Readily installed and replaced by a user”

The case Hearing Components v Shure involves an issue of claim indefiniteness from a term in the preamble:

As an initial matter, the “readily installed” phrase is a claim limitation, as Shure
argues. A preamble to a claim may or may not be limiting, depending on the
circumstances. “In considering whether a preamble limits a claim, the preamble is
analyzed to ascertain whether it states a necessary and defining aspect of the invention,
or is simply an introduction to the general field of the claim.” Computer Docking Station
Corp. v. Dell, Inc., 519 F.3d 1366, 1375 (Fed. Cir. 2008) (quotation marks omitted). A
term is often limiting when the patentee has relied on it during prosecution to distinguish
prior art, as such reliance demonstrates that the feature disclosed in the preamble is
necessary to the patentability of the claim. See id.; Jansen v. Rexall Sundown, Inc.,
342 F.3d 1329, 1333 (Fed. Cir. 2003). In this case, Hearing Components clearly relied
on the “readily installed” phrase during prosecution to distinguish prior art.

Of indefiniteness:

“Claims are considered indefinite when they are not amenable to
construction or are insolubly ambiguous. Thus, the definiteness of claim terms depends
on whether those terms can be given any reasonable meaning. Indefiniteness requires
a determination whether those skilled in the art would understand what is claimed.”
Young, 492 F.3d at 1346 (internal citations and quotations marks omitted). The
purpose of the definiteness requirement is to ensure that “the claims, as interpreted in
view of the written description, adequately perform their function of notifying the public
of the scope of the patentee’s right to exclude.” Honeywell Int’l, Inc. v. Int’l Trade
Comm’n, 341 F.3d 1332, 1339 (Fed. Cir. 2003) (quotation marks omitted).

(...)

“[A] patentee need not define his invention with mathematical precision in
order to comply with the definiteness requirement.” Invitrogen Corp. v. Biocrest Mfg.,
L.P., 424 F.3d 1374, 1384 (Fed. Cir. 2005) (quotation marks omitted). Not all terms of
degree are indefinite. However, the specification must “provide[ ] some standard for
measuring that degree.” Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342,
1351 (Fed. Cir. 2005) (quotation marks omitted).