SS.18 : Single-seat prototype.
The aircraft was fitted with a 450-hp (336-kW) Bristol Mercury IIA radial piston engine.

SS.18A : The SS.18 was fitted with a 480 hp (358 kW) Bristol Jupiter VIIF radial piston engine.

SS.18B : The SS.18 was later fitted with a 560 hp (418 kW) Armstrong Siddeley Panther III radial piston engine.

SS.19 : Single-seat prototype; fitted with a Bristol Jupiter radial piston engine.

SS.19A : The SS.19 was later fitted with two wheel spats and a single spatted tailwheel.

SS.19B : Single-seat prototype; fitted with a 536 hp (400 kW) Bristol Jupiter VIS radial piston engine.

Gauntlet Mk I : Single-seat fighter aircraft for the RAF; 24 built.

Gauntlet Mk II : Single-seat fighter aircraft; modified version of the Gauntlet Mk I; 221 built.
SS.18 : Single-seat prototype. The aircraft was fitted with a 450-hp (336-kW) Bristol Mercury IIA radial piston engine.
SS.18A : The SS.18 was fitted with a 480 hp (358 kW) Bristol Jupiter VIIF radial piston engine.
SS.18B : The SS.18 was later fitted with a 560 hp (418 kW) Armstrong Siddeley Panther III radial piston engine.
SS.19 : Single-seat prototype; fitted with a Bristol Jupiter radial piston engine.
SS.19A : The SS.19 was later fitted with two wheel spats and a single spatted tailwheel.
SS.19B : Single-seat prototype; fitted with a 536 hp (400 kW) Bristol Jupiter VIS radial piston engine.
Gauntlet Mk I : Single-seat fighter aircraft for the RAF; 24 built.
Gauntlet Mk II : Single-seat fighter aircraft; modified version of the Gauntlet Mk I; 221 built.
Gloster Gauntlet