A rigid, channel-framed, non-compressible, non-nestable, pleated air filter, comprising: a tightly-pleated air filter media comprised of a nonwoven fibrous web and with an upstream face and a downstream face, wherein the tightly-pleated air filter media comprises a plurality of upstream (and downstream) pleat tips and upstream (and downstream) pleat valleys, the tightly-pleated air filter media comprising a plurality of upstream (and downstream) linear bridging filaments that are at least substantially parallel to each other and are oriented at least substantially orthogonal to the pleat direction and are extrusion-bonded to at least some of the upstream (and downstream) pleat tips, and, a channel frame comprising four major frame portions, with each major frame portion being mounted on one of the four major edges of the pleated air filter media.