The base oil helps to spread the active ingredients through your hair as well as providing particular benefits. As everyone's hair is different and prefers different oils, you have a choice. Not sure which base oil to choose? Take your pick:

• Coconut Oil - Fractionated Coconut Oil, is a feather-light emollient that softens and hydrates your hair. It leaves your hair feeling silky and smooth without a greasy aftereffect. However, some find coconut oil can leave their hair a little "crunchy".
• Macadamia Oil - is rich in fatty acids and potassium. Its concentration of palmitoleic acid, in particular, makes it great at smoothing hair. Like coconut oil, it penetrates hair more efficiently than many other oils. As a tree nut, it can cause issues in people with allergies.
• Avocado Oil -Rich in vitamins A, B1, B2, B5, D & E as well as minerals, protein, Lecithin and fatty acids. Avocado oil can be a heavier oil which means it less suitable for those with fine hair.
• Sweet Almond Oil - conditions and moisturizes dry hair, improves scalp health, prevents hair breakage. In general, it's suitable for all hair types but best for dry and/or damaged hair; those with very fine hair should apply sparingly. Again, those with nut allergies should avoid almond oil.

How about essential oils?

• None - great for pregnant or breastfeeding people  or others who are advised to avoid many essential oils or those with sensitive noses.
• Rose - a classic rose scent mix, what's not to love?
• Goddess - a fascinating mix of floral citrus
• Herbilis - a fresh grassy mix with subtle florals - it's as good for your hair as it smells.

Other great specialty oils included in every serum: 

• Pracaxi Oil - sometimes considered liquid gold, Pracaxi oil is a vitamin-rich hair oil that hydrates, promotes hair growth, and strengthens damaged hair.
• Abyssinian Oil - is an oil that is chemically closest to the natural oils produced by your skin. Abyssinian oil has concentrations of over 60% of C22 omega-9 long-chain fatty acids as well as C18 omega-6 and omega-9, much higher than in any other natural oil. These fatty acids can create a net-like structure around the hair, keeping cuticles closed and protected, while locking the moisture inside the hair. 
• Argan Oil - contains oleic and linoleic acids which can are great moisturisers. It also provides sun protection.
• Broccoli Oil - contains a unique fatty acid composition that is similar to silicone. This erucic acid (an omega-9 fatty acid) gives your hair a smooth natural sheen without leaving residue of harmful detergents or chemicals.