Pentax T Ring

Hi all new to the forum and just bought my first telescope, need some advice after purchasing Skywatcher 2x Deluxe Achromatic 1.25" Barlow which can be fitted with a T accept a DSLR camera. I have a Pentax K-R camera which which is compatible with KAF3, KAF, and KA mount lenses. Where can I buy a T ring that is compatible with this set up.
Steve
Steve