Specifically designed for Green Forest vernier calipers; other brands’ caliper bodies can also be used as long as their cross-sectional area is smaller than the internal rectangular dimensions of the holder. (The internal rectangular dimensions are 6.5 × 17 mm; see the accompanying illustration.)

There are two versions: a sticker version that uses nano double-sided tape (available on Taobao for about RMB 1–2 per roll—often readily available at home) to affix the device to the wall; and a magnet version that requires two rectangular magnets measuring 10 × 20 × 3 mm, which can be attached to a pegboard.