Side-by-side comparison of specifications and features
Compare visual case presence and physical footprint on one shared wrist. Measure your top-down wrist width for a stronger result; lug-to-lug is used when the catalog has it.
Medium (6.7″)
Estimated top width: 56.7 mm
Preliminary range: 54.7–61.8 mm.
Watch A
Visual presence
ModerateCase covers 67% of your modeled wrist width.
Physical footprint
Clear spaceEstimated clearance: 5.3 mm per side.
Watch B
Visual presence
BoldCase covers 71% of your modeled wrist width.
Physical footprint
Clear spaceEstimated clearance: 6.0 mm per side.
Proportional guide only: visual presence and physical footprint do not predict comfort. Weight, thickness, caseback shape, rigid lugs, strap stiffness, wrist-bone prominence, wearing tension, bezel design, and case curvature change how a watch actually wears. Non-round silhouettes use a verified family shape and catalog dimensions where available; missing case height or width is estimated from a conservative family aspect ratio.
Start with the specifications that meaningfully differ. Expand the complete table for reference details and missing-data context.
| Specification | Seiko Prospex | Tissot PRX Powermatic 80 |
|---|---|---|
| Pricing | ||
| MSRPPRX Powermatic 80 is $30 less at MSRP | $725 | $695 |
| New PriceProspex is $300.5 less based on the current snapshot | $529 | $830 |
| Used Price (Low)Prospex is $240.5 less at the low end | $319 | $559 |
| Used Price (High) | $3,750 | $1,245 |
| 30-Day Trend | ↓ -17.8% | ↓ -4.1% |
| Used Price Range | $319 - $3,750 | $559 - $1,245 |
| Identity | ||
| Style | Field, Sports, Tool | Sports, Dress |
| Dimensions | ||
| DiameterProspex is 2mm smaller | 38mm | 40mm |
| ThicknessPRX Powermatic 80 is 2mm thinner | 12.9mm | 10.9mm |
| WeightPRX Powermatic 80 is 6g lighter | 144g | 138g |
| Lug to Lug | 46mm | 44.6mm |
| Case | ||
| Water ResistanceProspex adds 100m water resistance | 200m (diving) | 100m (recreational diving) |
| Dial | ||
| Dial Color | Green | Blue |
1 field is excluded from the differences view because one watch lacks comparable data. Use “All specs” to inspect those gaps.
Seiko Prospex SPB155 (Baby Alpinist) and Tissot PRX Powermatic 80 can overlap on price or use case, but the buying decision usually comes down to wrist presence versus easier fit, water-ready utility versus dressier everyday wear, field character versus sports versatility. They both touch the sports use case, so smaller spec differences can matter more than brand preference.
Bottom line
Fit is a real separator here — compare case width and lug-to-lug before deciding, especially if wrist comfort matters more than headline features. Choose Seiko Prospex SPB155 (Baby Alpinist) if you want a smaller case footprint on the wrist; choose Tissot PRX Powermatic 80 if you prefer more dial presence and a larger case feel.
Choose Seiko Prospex SPB155 (Baby Alpinist) when
Seiko Prospex SPB155 (Baby Alpinist) is a better fit for smaller wrists, mechanical-watch enthusiasts, field styling.
Choose Tissot PRX Powermatic 80 when
Tissot PRX Powermatic 80 is a better fit for buyers who want more wrist presence, mechanical-watch enthusiasts, sports styling.
Movement and upkeep
Seiko Prospex SPB155 (Baby Alpinist): automatic movement
Tissot PRX Powermatic 80: automatic movement
Both use the same movement type, so maintenance differences are limited and fit or feature details should decide the purchase.
Size and wearability
Seiko Prospex SPB155 (Baby Alpinist): 38mm · L2L 46mm · 144g
Tissot PRX Powermatic 80: 40mm · L2L 44.6mm · 138g
Fit is a real separator here — compare case width and lug-to-lug before deciding, especially if wrist comfort matters more than headline features.
Water resistance
Seiko Prospex SPB155 (Baby Alpinist): 200m
Tissot PRX Powermatic 80: 100m
Water resistance is a meaningful separator here — the higher-rated option gives more flexibility for swimming or rougher daily use.
Price and value
Seiko Prospex SPB155 (Baby Alpinist): $529
Tissot PRX Powermatic 80: $695
There is a real price gap here — treat the more expensive option as an upgrade decision and confirm whether the extra spend buys something you will notice in weekly use.
Style and use case
Seiko Prospex SPB155 (Baby Alpinist): field
Tissot PRX Powermatic 80: sports
Seiko Prospex SPB155 (Baby Alpinist) leans more field, while Tissot PRX Powermatic 80 pulls toward sports use case — pick the one that matches how you will actually wear it.
Crystal and materials
Seiko Prospex SPB155 (Baby Alpinist): sapphire crystal · steel
Tissot PRX Powermatic 80: sapphire crystal · steel
Materials are broadly similar, so finish, fit, and price will matter more than the materials list alone.
Seiko Prospex SPB155 (Baby Alpinist) is often the value play at current pricing, while Tissot PRX Powermatic 80 makes more sense if you will use its extra features regularly.
There is a real price gap here — treat the more expensive option as an upgrade decision and confirm whether the extra spend buys something you will notice in weekly use.
Check current deals on Amazon and eBay using the buttons below — listing prices, seller quality, and condition can change quickly.
Prices change often, so compare the latest listings and condition options before you buy.
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Seiko Prospex
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Tissot PRX Powermatic 80
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Tissot PRX Powermatic 80 — it is 44.6mm lug-to-lug versus 46mm, and lug-to-lug is what decides whether a watch overhangs a smaller wrist.
Seiko Prospex SPB155 (Baby Alpinist) — it is rated 200m versus 100m. Both are in the same broad bracket, so treat this as a tiebreaker rather than a deciding factor.
Seiko Prospex SPB155 (Baby Alpinist) is the value pick at roughly $166 less. Pay more only if a specific difference above matters to you — otherwise the cheaper one is the smarter buy. Confirm live listings, since marketplace pricing moves.
Evidence & Method
This page currently relies on normalized catalog fields and calculated differences. No external reviewer observation is used in its verdict.
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