Two reviewers here independently say the same thing: some of the equipment doesn't fit shorter people, and the adjustment options won't fix it. That's the most useful finding on this page, and it comes from two people who otherwise rated the gym well.
First though, the date. Nothing has been written about Fressi 24h Herttoniemi since April 2019. That's over seven years. The 4.1 from 15 reviews is a small, old sample. Read everything below as a snapshot, and note that 15 ratings isn't much to lean on either way.
The Fit Problem, From Two Directions
A member in April 2019 (translated from Finnish), rating it four stars: "My own gym for five years now. Good location and enough equipment. But some of the machines are big and a short woman doesn't quite manage. I've tried to get the situation fixed, so far without success."
A member in August 2018 (translated from Finnish), rating it three stars: "A basic gym that surely has everything a regular exerciser needs. The bench and the squat rack have fixed adjustment options, which don't serve my own height."
Different people, different heights, eight months apart, both landing on the same defect: the adjustment increments don't cover them. One is a woman who says she's been asking for a fix for a while and getting nowhere. That last part is worth noticing, because it turns a hardware limitation into a service one.
Do I know if this was ever sorted? No. Both reviews are years old and the gym may have replaced everything since. But if you're short, this is the question to ask on the tour.
The Best Review on the Record
The three-star reviewer from August 2018 kept going, and he's the only person in this entire record who counted anything (translated from Finnish):
"There could be more weight plates, especially 20kg discs, because if there are more people doing free-weight movements, there may be a shortage of plates. Also 25kg plates would be welcome. Dumbbells go up to 40kg x 2. It wouldn't hurt if they went to 45 and 50kg. Plenty of room for stretching and other floor work. The space is open and doesn't feel cramped even with more people training."
Dumbbells to 40kg. Not enough 20kg plates at busy times. No 25kg plates at all. That's the kind of specific, checkable detail I wish every record had, and it's why a three-star review is often worth more than five five-star ones.
Notice he isn't unhappy. He calls it a basic gym with everything a regular exerciser needs. He just tells you exactly where the ceiling is. If you deadlift heavy, that ceiling is aimed at you.
The Air
A member in December 2018 (translated from Finnish): "A good gym with fairly comprehensive equipment for training. Plenty of space and little congestion. The changing rooms are tidy and the location is good. Open every day of the year around the clock. A minus is perhaps the slightly poor air circulation, which makes you get tired more easily than at many other gyms."
He's comparing it with other gyms he's used, and only on this one point does it lose. That's a considered complaint, not a grumble.
He's also the only source for the 24-hour claim. The name says 24h and he confirms it was open around the clock every day of the year in December 2018. No hours are published on the listing now, so I'd verify.
The Rest
A member in April 2019, three stars: "It's ok big space to train freely, but needs a lot more equipment."
A member in October 2018 (translated from Finnish), four stars: "A good gym with all the basic fitness machines and stretching space. Not too much congestion. Only the sauna is missing."
In Helsinki, "only the sauna is missing" is a real complaint. He rated it four stars anyway.
What's Missing and Who It's Not For
No prices anywhere. No phone number, only fressi24.fi. No hours on the listing despite the name.
Not for you if you're lifting near the top of the dumbbell rack, going by the 2018 inventory.
Not for you if you're short and can't work with fixed-increment benches, unless they've changed the kit.
Not for you if you want a sauna.
Linnanrakentajantie 4, 2nd floor, 00880 Helsinki. The site is fressi24.fi.
FAQ
How heavy do the dumbbells go?
To 40kg per hand, according to a member writing in August 2018. He wished they went to 50.
Is it really open 24 hours?
A member in December 2018 said it was open around the clock every day of the year. No hours are published on the listing now, so confirm at fressi24.fi.
Is there a sauna?
No. A member in October 2018 specifically notes its absence.
Are the machines suitable for shorter people?
Two members, in 2018 and 2019, both say the fixed adjustments didn't fit them. One reports asking for a fix without success. Whether it's been addressed since isn't recorded.