This has been a problem for the last few years when they started mixing
metric and imperial sizes, especially the "kink free" ribbed hose. I found
the best way is to use a fitting that is tight and soak the hose in hot
water as Tom mentions in his response below - don't worry about Beckett, any
barbed tee will do
Gale :~)

I cant find a 1 1/2 inch barbed tee for my beckett flex tubing. It looks
like pool type hose in black and more flexible. But every pool place and
hardware has 1 1/2 but the beckett is just I tiny bit smaller. Why do
they do that? I cant find any plastic parts or adapters to make up what
I need. Thank you