The engine runs well on air in either direction, with slight leakage past the regulator.
| gauge | Gauge 1 & smaller |
| length/inches | 20 |
| width/inches | 3 1/2 |
| height/inches | 5 |
| weight/kg | 5 1/2 |
| bore x stroke/inches | 4 cylinder, 11mm x 22mm |
| minimum radius/feet | 2 meter |
| cylinder material | gunmetal |
| valve type | slide |
| valve gear | Walschaerts |
| reverser type | screw |
| lubricator type | Roscoe displacement |
| boiler maker | Aster |
| CE mark | n/a - < 2 litre capacity |
| working pressure/psi | 4Kg/cm2 |
| boiler type | spirit-fired |
| boiler material | copper |
| boiler construction | silver soldered |
| superheater(s) | 2 |
| superheater type | flue tube |
| safety valve(s) | 2 (+ 2 dummy) |
| safety valve type | spring |
| mechanical pump | 1 x axle pump |
| hand pump | 1 |