Pick the head count from the job, then confirm with samples.
VL-SS (single-head, single-feeder)
One applicator, one reel, one material per part. Typical start for PCB/FPC, small housings, and a single label or auxiliary patch. Catalogue reference 1200–2000 labels/h, subject to sample validation.
VL-DD (dual-head, dual-feeder)
Two applicators and two reels in one pass. Use it when the same part needs two materials or two positions that can share one conveyor. Both targets, both materials, and replenishment have to work together.
VL-4H (three- or four-head)
Coordinated heads for repetitive batch work such as carrier-tape products. The catalogue allows three or four heads. Do not infer output from head count; pitch, feeder stability, and fixtures decide the rate. Catalogue reference 3000–4000 labels/h after a trial.
Robot cells (VL-4A, VL-DT) are a different fork: reach and orientation, not extra heads. If the part must be turned or picked from a tray, discuss the robot pages rather than adding heads to a conveyor machine.