Designed to be a straight fit onto the Revell kit (03097 and 03243). Three alternative fume extractors are provided with different textures. Check your references against the model you are building.
Remove the casting gates CAREFULLY. The fume extractor has a small hole at the front which needs to be drilled out to 3.2 mm. Drill this from the INSIDE/the rear. The rear has a wider opening to fit the kit mount.
Carefully align the parts. There is a small amount of play in the fume extractor to help you with this.
The sight on the collimator goes on the right side, not the top.