an unframed pleated air filter media with an upstream face and a downstream face,

wherein the unframed pleated air filter media comprises a plurality of oppositely-facing pleats with a pleat direction and with a plurality of upstream pleat tips and upstream pleat valleys and downstream pleat tips and downstream pleat valleys, the unframed pleated air filter media further comprising a plurality of bridging filaments on at least one face of the unframed pleated air filter media,

wherein at least some of the bridging filaments of the plurality of bridging filaments are in discontinuous contact with the upstream face of the unframed pleated air filter media and are bonded to at least some of the upstream pleat tips; or, are in discontinuous contact with the downstream face of the unframed pleated air filter media and are bonded to at least some of the downstream pleat tips;

wherein the unframed pleated air filter is conformable at least between a first, nominally planar configuration and a second, conformed configuration, the second, conformed configuration being an arcuate configuration in which the unframed pleated air filter exhibits single curvature with a conforming axis that is orthogonal to a pleat direction of the unframed pleated air filter and with an average radius of curvature of less than 100 cm;

and wherein the conformable, unframed pleated air filter is configured to be conformed to, and contacted with, an upstream face of an arcuate filter-support layer of an HVAC system, and to filter air that is pulled through the conformable, unframed pleated air filter when the HVAC system is operated.