The value priced Dive Alert™ Orange SMT is {65 in | 165 cm} by {8 in | 20.3 cm} and inflated with your second stage regulator. The nylon strap at the top provides an attachment point for a light or slate and two strips of reflective tape across the top significantly increases visibility. Constructed of durable 400 denier polyurethane coated nylon material in high visibility orange color on both sides and includes two hook and loop straps to retain a tidy compact roll for storage.

The semi-closed design is a hybrid of open and closed types that is open at the bottom and incorporates an funnel-shaped (aka "duck-bill") internal baffle that allows the tube to be inflated as usual with a regulator second stage at depth, but prevents the tube from unintentionally deflating should it fall over while on the surface. The hybrid marking tube includes an over pressure valve to allow excess gas to vent during ascent and pull dump to deflate the bag before boarding the boat or when being rolled up for storage.

A usage note... the hybrid SMT is not fully closed by design and if you inflate it when dry (i.e. at home, to 'test' it), you will discover gas slowly leaks out through the bottom baffle. This does not cause a problem in actual in-water use, where the water will cause the baffle to seal. Although the marking tube should NOT be used as a lift bag, for emergency purposes a fully inflated tube may be considered to have approximately { 30 lb | 14 kg } of lift when completely submerged.