As a simple rule of thumb the following guide applies - but as they say - measure twice, cut once! Make sure your awning is fully extended and the roller bar is set to the three O'clock position when measuring the size required.
Short - 2100-2200mm
- Generally suits Carefree roll out awnings on pop tops
Medium 2200-2300mm
- Generally suits Dometic roll out awnings on full vans and pop tops
Large 2300-2400mm
- Generally suits Carefree & Aussie Traveller Sunburst Eclipse awnings on full caravans
Please use the below resources to measure your awning for your Anti Flap Kit.
This Buying Guide discusses how to choose which AFK size to buy:
https://www.campsmart.net.au/buying/buying-guides/confused-about-which-sized-anti-flap-kit-to-buy/
You may also find this video useful as it shows you how to set your awning at the 3 O'clock position