Before you specify
Frequently Asked Questions
What exactly is the cut size, given the conflicting figures?
The metric figure is 3.9 x 40 mm, and it is the one the P-4 rating is based on: 156 mm² against the DIN 66399 limit of 160 mm². Kobra's own US material is inconsistent on the imperial conversion — the datasheet prints 1/8 x 1-1/2 in. and the US product page prints 3/16 x 1-1/2 in. The latter works out at roughly 181 mm², which would be P-3, so treat the metric dimensions as definitive.
Can it shred staples, paper clips and stapled sets?
Yes. Kobra specifies carbon-hardened steel cutting knives that are unaffected by staples and paper clips, so you can feed stapled files directly. Remove ring binders, plastic combs and large binder clips first. Continuous staple feeding is not a problem for the knives but it does blunt the effective sheet capacity, because a stapled set behaves like thicker stock.
How much oil does the automatic oiler use?
Kobra supplies oil for this model as art. SO-1032, a 7 oz bottle. Consumption depends entirely on usage — a machine shredding a few reams a week will go months on a bottle, and a records-room purge will consume noticeably more. Use Kobra shredder oil rather than a general lubricant or an aerosol; the wrong product can leave residue that a cross-cut head does not clear.
Is it NSA approved?
No. NSA/CSS Specification 02-01 requires a maximum 1 x 5 mm particle and a listing on the NSA/CSS Evaluated Products List; a 3.9 x 40 mm cross-cut particle satisfies neither. P-4 is a commercial confidentiality level, not a government destruction standard. The NSA-listed machine in this cabinet family is the KOBRA 400 HS-6 AUTO-OILER.
How does it compare with the 310 TS CC4 AO?
Same cut — 3.9 x 40 mm at P-4 — and both have an automatic oiler. The 390 C4 is the larger machine: 16-inch throat instead of 13, 53-gallon bin instead of 40, 33 sheets instead of 31, 169 lb instead of 121. The 310 TS gains a touch-screen panel with a live load readout and a separate optical media cutting unit, which the 390 C4 does not have. Choose on throat width and disc handling, not on security class.
How often will the bin need emptying?
Cross-cut waste compacts far better than strip cut, so the 53-gallon bag holds a substantial weight of paper. A department of 40–60 people typically changes it every one to two weeks in normal use. During an archive purge, expect a change every few hours. The machine stops automatically when the bag is full.
Is it quiet enough for an open-plan office?
At 58–61 dB(A) it is about as loud as a normal conversation held nearby, and it is only that loud while it is actually cutting. That is acceptable next to a print room or in a copy alcove. It is noticeable if it sits three feet from someone's desk in a quiet open-plan floor — site it with the printers rather than with the people.