Budget anti-heat stainless steel cylinder from XT.  The vents are 36mm from the cylinder end, also referred to as 1/2 cylinder.  Machining is pretty decent with no reported burrs on the vents however I recommend checking and if so sanding them down, this will help preserve the piston head o-ring.  The inside surface has been plasma polished.

Specifications
Material: Stainless steel
Vents: 4 (36mm distance of the vent to the cylinder head end)
Internal Diameter: 23.7mm
Outer Diameter: 25.4mm
Length: 72mm
Weight: 30g
Recommended Barrel Length: 94mm - 208mm

Cylinder Size Guide