Scubapro Universal 200 / 300 Bar Din Kit For Regulators From  £39.99

Perfect for the job, fitted to my MK25 in 5 minutes by my local dive shop tech in exchange for a packet of biscuits!
Have used it in anger now, no leaks, very pleased.
Great service from Jackson too

I bought two of these to convert two of my ScubaPro first stages to din. The conversion is simple once you have removed the old A-Clamp. You have to be careful however as there are two got-yas. The first got-ya is that you have to remove the outer section to be able to screw the clamp in properly and safely. The second got-ya is you have to tighten it up to a certain torque setting otherwise you can split the case. I would recommend letting a ScubaPro proffesional to install it but the product works well.