Sugatsune's ALT-ST is a cabinet pocket door system: the ALT-ST20-D10 installation manual calls it "hardware for vertical pocket doors in furniture, enabling slow door closing", with the door stored inside the cabinet. This guide explains the item numbers and links the installation manual for each of the four systems.
How to read an ALT-ST item number
Each system is ordered as a parts set. Sugatsune's General Catalog 501 splits a parts set name such as ALT-ST15-D10 S - 16 into a type name and a slide length. Taking ALT-ST20-D360LL-28 as an example:
- ALT-ST20 - the family: ALT-ST15 or ALT-ST20 (compared below).
- D360 - the inset system. D10 is the overlay system.
- LL - the type: S, M, L or LL. The type sets the door height range; Sugatsune's tables also give the maximum door weight and the number of slides for each type.
- 28 - the slide length in inches: 16, 19, 22, 24 or 28.
ALT-ST15 or ALT-ST20: door height, weight and slides
All four systems take doors up to 24 in. (610 mm) wide. The ALT-ST15 tables cover doors 19-11/16 to 63 in. (500-1600 mm) tall and up to 33 lbs (15 kg); the ALT-ST20 tables cover 31-1/2 to 94-1/2 in. (800-2400 mm) and up to 44 lbs (20 kg). For both ALT-ST15 systems, Sugatsune states that the fittings allow the door to retract further into the cabinet than the matching ALT-ST20 system. The same type letter means a different door height in ALT-ST15 and ALT-ST20, so check the letter against these tables:
Door height by type
| Type | ALT-ST15 | ALT-ST20 |
|---|---|---|
| S | 500-700 mm (19-11/16 to 27-9/16 in.) | 800-1200 mm (31-1/2 to 47-1/4 in.) |
| M | 700-900 mm (27-9/16 to 35-7/16 in.) | 1200-1600 mm (47-1/4 to 63 in.) |
| L | 900-1200 mm (35-7/16 to 47-1/4 in.) | 1600-2000 mm (63 to 78-3/4 in.) |
| LL | 1200-1600 mm (47-1/4 to 63 in.) | 2000-2400 mm (78-3/4 to 94-1/2 in.) |
Maximum door weight and number of slides
| Type | ALT-ST15 | ALT-ST20 |
|---|---|---|
| S | 19.8 lbs (9 kg), 2 slides | 19.8 lbs (9 kg), 2 slides |
| M | 19.8 lbs (9 kg), 2 slides | 33 lbs (15 kg), 3 slides |
| L | 33 lbs (15 kg), 4 slides | 44 lbs (20 kg), 4 slides |
| LL | 33 lbs (15 kg), 4 slides | 44 lbs (20 kg), 4 slides |
Inset D360 or overlay D10
- D360, inset: the brochure says these systems use 360 Olympia hinges, and the catalog's D360 parts lists show a hinge body with a built-in damper. Door thickness 11/16 to 1-3/16 in. (18-30 mm); hinge cup bore (door cut-out) 40 mm in diameter, 15 mm deep.
- D10, overlay: overlay amount up to 3/8 in. (10 mm), with an overlay damper unit (with adjustment screw) included. The 2026 catalog adds: "Hinges include an integrated catch function; for catch-only applications, do not install the damper." Door thickness 11/16 to 13/16 in. (18-20 mm); hinge cup bore (door cut-out) 40 mm in diameter, 13 mm deep.
Our concealed cabinet hinge guide explains overlay and inset.
Slide length and minimum cabinet depth
The last digits are the slide length, and the manuals warn: "Do not cut rails." For each length the brochure lists a door storage amount and a minimum cabinet depth. The minimum cabinet depths below are the same for ALT-ST15 and ALT-ST20; for the inset systems, add the door thickness.
| Last digits | D10 (overlay) | D360 (inset), plus door thickness |
|---|---|---|
| 16 | 16-9/16 in. (420 mm) | 16-1/4 in. (412 mm) |
| 19 | 19-1/2 in. (496 mm) | 19-3/16 in. (488 mm) |
| 22 | 22-1/2 in. (572 mm) | 22-3/16 in. (564 mm) |
| 24 | 24-1/2 in. (623 mm) | 24-3/16 in. (615 mm) |
| 28 | 28-9/16 in. (725 mm) | 28-1/4 in. (717 mm) |
The door storage amount differs between ALT-ST15 and ALT-ST20: with 16 in. slides it is 12-3/8 in. (315 mm) for the ALT-ST15-D10 and 10-9/16 in. (268 mm) for the ALT-ST20-D10. For how far a fully pocketed door protrudes from the cabinet face, the catalog gives Protrusion = Door Width - Door Storage Amount for the overlay systems and Door Width - (Door Storage Amount + Door Thickness) for the inset systems.
What a parts set includes
The catalog marks the parts set "Not optional. Each set includes required parts." Its parts-set pages list the slides (their item number ends with the same digits as the set), a synchronized board, hinges with mounting plates and small parts such as catches, rollers and adjustment bolts: "Necessary types and numbers of screws and hexagon wrenches are included." The catalog also notes: "To hide the metal fittings, install a middle board (not included)."
ALT-ST installation manuals (PDF)
Sugatsune's product pages link these 9-page manuals under Downloadable Files:
- Installation Manual ALT-ST15-D10 (overlay)
- Installation Manual ALT-ST15-D360 (inset)
- Installation Manual ALT-ST20-D10 (overlay)
- Installation Manual ALT-ST20-D360 (inset)
Each manual lists the parts and quantities for each type, then numbered steps: mounting the rollers, the slide rail catch and rail layout, the mounting plates and connecting bar, hinge positions on the door, hanging the door, the 5-stage door angle adjustment, and depth, vertical, horizontal and closing speed adjustment. The two inset manuals open with this note: "For the most accuracy, please use metric measurements as they were converted to imperial measurements for reference." They then give door width and height formulas based on the cabinet opening. The first page of the two overlay manuals has an item name guide and a specification table.
Each manual cautions: "Provide a cabinet that can withstand the weight and impact of opening and closing the door. Be sure to use the specified screws and tighten them securely. If the mounting strength is insufficient, the door may fall and can cause injury." The manuals also say not to force the door open past 90 degrees and recommend checking the screws for slack one month and six months after first use, then once a year.
Hinge and slide placement tables for each type are also in the ALT-ST brochure and the Cabinet Systems chapter of General Catalog 501 (pages 438-461).
Sugatsune ALT-ST systems at The Builders Supply
A selection of our pages; door heights in parentheses are Sugatsune's ranges:
- ALT-ST15-D10, overlay: ALT-ST15-D10M-16 (700-900 mm) and ALT-ST15-D10LL-19 (1200-1600 mm)
- ALT-ST15-D360, inset: ALT-ST15-D360S-22 (500-700 mm) and ALT-ST15-D360LL-19 (1200-1600 mm)
- ALT-ST20-D10, overlay: ALT-ST20-D10S-22 (800-1200 mm) and ALT-ST20-D10L-22 (1600-2000 mm)
- ALT-ST20-D360, inset: ALT-ST20-D360L-24 (1600-2000 mm) and ALT-ST20-D360LL-28 (2000-2400 mm)
- All Sugatsune products and the Sliding and Folding Cabinet Door Hardware category
For another maker's sliding and pocket door hardware, see our Hafele Slido guide.
Not sure which type or slide length fits your cabinet? Our customer support team is available Monday - Friday, 8 AM - 4 PM Central Time, at 1-888-800-7789 or [email protected].
