Place 6 clean 250 or 236 ml mason jars on a rack in a boiling water canner; cover jars with water and heat to a simmer (180°F/82°C). Set screw bands aside; heat SNAP Lids in hot water, NOT boiling (180°F/82°C). Keep jars and SNAP Lids hot until ready to use.
Wash, hull and crush strawberries, one layer at a time. Measure 2 cups (500 ml); set aside.
Wash and finely chop rhubarb. Measure 2 cups (500 ml); set aside.
Measure sugar; set aside.
Combine prepared strawberries, rhubarb and lemon juice in a large, deep stainless steel saucepan. Whisk in Fruit Pectin until dissolved.
Stirring frequently, bring mixture to a boil over high heat. Add sugar. Stirring constantly, return mixture to a full rolling boil; boil hard 1 minute. Remove from heat; skim foam.
Ladle jam into a hot jar to within ¼ inch (0.5 cm) of top rim (headspace). Using nonmetallic utensil, remove air bubbles. Wipe jar rim removing any stickiness. Center SNAP Lid on jar; apply screw band securely & firmly until resistance is met — fingertip tight. Do not overtighten. Place jar in canner; repeat for remaining jam.
Cover canner; return water to a boil. At altitudes up to 1000 ft (305 m), process –boil filled jars – 10 minutes.* Remove jars without tilting. Cool upright, undisturbed 24 hours; DO NOT RETIGHTEN screw bands. After cooling check jar seals. Sealed lids curve downward. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars, as desired. Label and store jars in a cool, dark place.