This is the valve housing with the full power exhaust port so you will have to tune your air rifle down if you are in the UK to stay within sub 12 or those that are not in the UK or have a full FAC can get the full power of this rifle with this part. Please note this only fits Artemis M30, SPA M30 and Snowpeak M30 NOT THE M30B AS IS A DIFFERENT VALVE HOUSING, I know because I bought it for my S owpeak .30b thinking it was the same and then when arrived it clearly was different model. NO RETURNS SO PLEASE ENSURE IS TH CORRWCT PART BEFORE BUYING.