Ergonomics and sizing
This is proposed physical-product guidance, not approved Thorbis rules. src/data/product-guidelines.ts is the canonical owner of wording, reasons, status, and sources; product-guidelines-why.ts is a derived compatibility export. This Markdown is generated, not independently maintained.
Lead with the body, then the mechanism. Sizes publish height, weight, and max load. Ranges are numbers, in the same units as the size guide.
Lead with the body.
pd-ergo
Status: proposed.
Say the human outcome before the part name: pressure in the seat, a curve that meets the spine, a reach to the control, a wrist that stays neutral. The TITAN Evo page puts the pebble seat and the lumbar system next to how a person moves, not as a bare trademark.
Why: People buy a chair for their back, not for a lattice of hinges; say the body outcome first.
Sources: Secretlab TITAN Evo features (opens in a new tab), Secretlab SoftWeave Plus (opens in a new tab)
Publish height, weight, and max load.
pd-size
Status: proposed.
Every size gets a recommended height, a recommended weight, and a maximum load, and those are three different numbers. Secretlab's 6 June 2026 size guide prints TITAN Evo Small at or under 169 cm and under 90 kg, Regular at 170 to 189 cm and under 100 kg, and XL at 181 to 205 cm and 80 to 180 kg. The Secretlab SG FAQ adds the max weight: Small 130 kg, Regular 130 kg, and XL 180 kg. The 180 kg figure is the XL limit, not the limit for Small or Regular.
Why: Recommended weight is not the maximum load, so using the smaller number as the limit, or the largest size's limit for every size, orders the wrong chair.
Sources: Secretlab, TITAN Evo size guide, 6 June 2026 (opens in a new tab), Secretlab SG FAQ, TITAN Evo max weight (opens in a new tab)
Print the adjustment range.
pd-ergo-range
Status: proposed.
The word adjustable is not a spec. Publish degrees, centimeters, and kilograms: seat height, recline, armrest travel, desk height. MAGNUS Pro lists a height range and a max weight on the product page.
Why: Adjustable is not a range; degrees, centimeters, and kilograms are.
Sources: Secretlab MAGNUS Pro (opens in a new tab), TITAN Evo technical specification (opens in a new tab), Secretlab TITAN Evo features (opens in a new tab)
Name the contact surface.
pd-ergo-contact
Status: proposed.
Identify what touches the person and what it is for. Cold-cure foam is specified as medium-firm for support. A magnetic head pillow is there for the neck, and it snaps on without straps. A steel desktop is not the work surface; the mat is.
Why: Comfort is decided where the body meets the product, so naming that surface and its job turns a comfort promise into something a buyer can check.
Sources: Secretlab TITAN Evo features (opens in a new tab), PCMag, MAGNUS Pro review (opens in a new tab), Mediaberry, MAGNUS Pro review (opens in a new tab)
Say which size when they overlap.
pd-size-overlap
Status: proposed.
Regular and XL both cover some heights. When two sizes fit, the page says who should choose which, and why. Leaving that blank turns into a return.
Why: Where two sizes both fit, say who should pick which; silence there becomes a support ticket.
Sources: Secretlab TITAN Evo features (opens in a new tab), Secretlab FAQ, assembly and magnets (opens in a new tab)
Print the hinge range for that generation.
pd-hinge-stated
Status: proposed.
The 18 June 2012 Surface release describes a built-in kickstand and does not give it a degree range. The 22-degree figure in that release is the angle of the chassis edge, not the hinge. Surface Pro 3's note states a friction hinge from zero to 150 degrees. The May 2017 Surface Pro spec and the Surface Pro 7 fact sheet state a full-friction multi-position hinge to 165 degrees, and the 2017 note ties that end to writing and drawing. The 11th Edition fact sheet repeats a kickstand with a 165-degree full friction hinge. Print the stated range for that generation, and the posture the end of the range is for.
Why: The stated Surface hinge range grew from 150 to 165 degrees between generations, so a range copied from an older page is wrong for the one on sale.
Sources: Microsoft, Surface announcement, 18 June 2012 (opens in a new tab), Microsoft Devices Blog, Surface Pro 3 (opens in a new tab), Microsoft UK Stories, Surface Pro, May 2017 (opens in a new tab), Surface Pro 7 fact sheet, October 2019 (opens in a new tab), Surface Pro 11th Edition fact sheet, 2024 (opens in a new tab)
State the display ratio and the work it is for.
pd-display-ratio
Status: proposed.
Panos Panay's 20 May 2014 Surface Pro 3 note says the 3:2 ratio came from a piece of paper, so the 12-inch 2160 by 1440 screen would feel familiar in portrait and in landscape. The 19 May 2026 Surface for Business note says the 3:2 ratio is a productivity choice: vertical space for two documents side by side. The 11th Edition fact sheet prints aspect ratio 3:2 at 2880 by 1920. Print the ratio and the work it is for.
Why: Microsoft chose 3:2 for paper-shaped pages and two documents side by side, and a buyer can weigh that choice only when the page names the work.
Sources: Microsoft Devices Blog, Surface Pro 3 (opens in a new tab), Microsoft Devices Blog, Surface for Business, 19 May 2026 (opens in a new tab), Surface Pro 11th Edition fact sheet, 2024 (opens in a new tab)