Thomas & Betts YLS-7.9-840BC CABLE TIE 100LB 33IN 316SS BLK COAT

316 stainless is the grade you pick for salt air, chemical exposure, and washdown, and the YLS-7.9-840BC adds a black polymer coating over the 316 band. The coating does two jobs on a job site: it keeps the bare steel from galling painted or coated conduit and cable jacket, and it hides the shine on exterior runs. For rooftop, marine, wastewater, tunnel, and food-plant work this is the tie spec people write.

Ball-lock is a stainless ball bearing captured in the head that wedges against the band, so the tie ratchets one way and will not release. You thread the tail, pull it up by hand, then use a stainless tie tensioning and cut-off tool to draw it to final tension and shear the tail flush. Hand-pulling alone leaves it loose and leaves a sharp tail sticking out, so budget for the tool if you do not already run one.

Nylon is the default indoors and in conditioned space, and it is fine there. Stainless goes in where nylon fails: UV on exterior runs, high heat, chemical exposure, and anywhere a code or spec calls out metal banding. Coated 316 like the YLS-7.9-840BC is the step past plain stainless, for salt exposure or where you do not want a bare steel band against a coated surface. The tradeoff is that it needs a tool and the tail has to be cut clean.

YLS-7.9-840BC is the Thomas and Betts designation, and the number reads directly: 7.9 is the band width in millimetres, 840 is the length in millimetres, BC is black coated. That naming runs across the YLS family, so a shorter version of the same band carries the same 7.9 prefix with a different length number.

That is what the coating is for. A bare stainless band can score paint, galvanizing, and cable jacket when it is tensioned down; the black polymer coating on this 316 band puts a softer layer between the steel and whatever it is wrapping. It also cuts reflection, which is why it gets specified on exposed exterior and architectural runs.