Heavy bottom cap for euphonium, supervised by Glenn Van Looy, euphonium player. Made in the UK, compatible with Besson Sovereign. Attaches to the 4th piston. The bottom cap can be disassembled, allowing you to reduce the weight and change the resistance. Please refer to the manufacturer's website. https://www.heavybottomcaps.co.uk/glenn-van-looy-abcs The new price is approximately £78.95 + £16.82 shipping from the UK.