SARMs for Bulking & Lean Muscle
About this range
Selective androgen receptor modulators in this collection are the compounds most often studied in published research on lean mass and muscle: Ostarine (MK-2866), Ligandrol (LGD-4033), Testolone (RAD-140), Myostine (YK-11) and the growth hormone secretagogue Ibutamoren (MK-677), alongside the Dexterz Labs muscle stacks that combine them.
Every Dexterz Labs product is manufactured in the United Kingdom to a fixed strength per capsule and carries a batch number on the bottle. Every batch is independently tested and its certificate of analysis is published on the product page and on the Lab Testing page.
Before choosing a compound, read the research guides: Ostarine (the only SARM with phase III data), LGD-4033, RAD-140, MK-677 and SARMs studied for lean mass. Each guide sets out what the trials found, the doses used in the research, the side effects reported and the legal position in the UK in 2026.
Products are supplied strictly for laboratory research and are not for human consumption. Nothing on this site is medical advice. 18+ only.
Single bottles, stacks or the Mass Series
This collection holds three kinds of product. Single compounds come as one bottle of 90 capsules at a fixed strength, such as Ostarine 10mg or RAD-140 5mg. The muscle stacks bundle separate labelled bottles for less than the singles cost together: the Beginner Muscle Stack pairs LGD-4033 with RAD-140, the Intermediate Muscle Stack adds MK-677, and the Advanced Muscle Stack adds YK-11. The Mass Series combines four compounds in one capsule instead of four bottles.
Frequently asked questions
What is the difference between the Mass Series and the Advanced Muscle Stack?
Both contain MK-677, LGD-4033, RAD-140 and YK-11. The Advanced Muscle Stack supplies them as four separate bottles of 90 capsules, each at its own strength. The Mass Series puts all four into a single capsule, 60 capsules per bottle, with the amount of each compound listed on the product page.
Are the stacks cheaper than buying the bottles separately?
Yes. Every stack is priced below the total of the single bottles it contains, and the contents of each bottle are the same as the single product.
How quickly is my order sent?
Orders placed before 2 pm Monday to Friday are dispatched the same working day in plain packaging, with free tracked UK delivery on orders over £60.