Mcmaster: a phone-and-desktop teardown
We loaded https://mcmaster.com 4 times on a simulated iPhone and 2 more on a 1366px desktop, and wrote down what a real visitor would see on each. No login, no insider access, no Harvv pixel needed. Here is what repeated visits already show, sorted by how we know it.
TL;DRWhat jumped out
Of everything we found on this scan, this is the one to start with: Images without sizes set make the page jump as it loads. 30 of 30 images on this page don't have width and height set. As each image finishes loading, the content below it slides down to make room. The visitor goes to tap one thing and ends up tapping another, and the cause is invisible to them.
Below: what's already working, every finding ranked by impact and tagged with the screen it affects, the speed numbers on phone and desktop, and a checklist of what to fix first.
00What's already working
Start here so the problems below are in context. These held up across the test loads:
- Speed is good. The main content paints in about 0.5s in our test loads, inside Google's 2.5s "good" threshold. Real networks are slower, but the page itself is not heavy.
- Light page weight. The page is about 0.7 MB across 59 requests. That keeps it quick on mobile data and cheap to load repeatedly.
- No JavaScript errors on load. Nothing threw a script error across the test loads, so buttons and tracking are not silently breaking mid-session.
- Search basics are in place. Lighthouse scores SEO 92/100. The fundamentals Google looks for are present.
- Accessible to most visitors. Lighthouse accessibility is 92/100, so screen-reader and contrast basics are largely handled.
- Layout holds on phone and desktop. Nothing spilled past the edge at either 390px (phone) or 1366px (desktop), so the structure is responsive.
01Findings, ranked by what hurts conversion most
| Severity | Finding | How we know |
|---|---|---|
| High | Images without sizes set make the page jump as it loadsBoth 30 of 30 images on this page don't have width and height set. As each image finishes loading, the content below it slides down to make room. The visitor goes to tap one thing and ends up tapping another, and the cause is invisible to them. | identical every load |
| Medium | Google is writing your search snippet for youBoth This page has no meta description, so Google grabs whatever text it finds on the page and shows that under your title in search results. Usually it's not the pitch you'd write yourself. Adding a 120–160 character summary is one of the easier wins for search click-through. | identical every load |
| Low | Search-result title is leaving room on the tableBoth Google gives you about 60 characters of headline space in search results. This page is using 13. Adding the value proposition or a relevant keyword gives someone one more reason to click. | identical every load |
| Low | No canonical tag, so duplicate URLs split the page's rankingBoth When the same content is reachable at multiple URLs (think tracking parameters or session IDs), Google can split your ranking signal across them. A single canonical tag tells Google which version counts. | identical every load |
"How we know": identical every load = a deterministic fact (e.g. element sizes). median across loads = a noisy lab metric, reported as a median. real-user field data = Google CrUX, actual Chrome visitors.
02Performance: phone, desktop, and real visitors
| Metric | Mobile | Desktop | Read |
|---|---|---|---|
| TTFB (lab median) | 155 ms | 139 ms | Lab |
| FCP (lab median) | 416 ms | 274 ms | Lab |
| LCP (lab median) | 450 ms | 290 ms | Good |
| Page weight (median) | 0.7 MB | 1.5 MB | OK |
Google Lighthouse (lab): Performance 72 mobile / 98 desktop, SEO 92, Accessibility 92, Best Practices 96.
Lab numbers are from a headless mobile browser on an unthrottled connection: treat them as a floor, not a typical experience. Add a Google API key to light up real-user field data (CrUX) and Lighthouse scores.
03Tiny buttons are hard to tap on mobile
6 of 32 tappable items on this page come in below 44×44 pixels, the size Apple and Google both recommend for reliable tapping on a phone. The same ones came up small on every one of the 4 test loads, so this is the page itself, not a fluke.
The buttons measuring below the minimum on this scan:
- a 390x30 ""
- button 16x16 ""
- button 24x24 ""
- a 64x35 "ORDER"
- button 40x40 "open menu"
- a 246x12 "Terms and Conditions and Pri"
The fix is CSS-only on most sites: add padding around the icon (don't just change the icon size) so the actual tap area is at least 44×44 pixels. No redesign, no new assets.
04Technical SEO & structured data
| Check | Result |
|---|---|
| Title | McMaster-Carr (13 chars) |
| Meta description | Missing |
| H1 | 1 on page |
| Canonical | Missing |
| Structured data (JSON-LD) | None |
| Open Graph | Incomplete |
05The fix checklist
Everything to fix, priority first, each tagged with the screen it affects and a rough effort. Work top to bottom.
- Images without sizes set make the page jump as it loadsBothCSS only
- Google is writing your search snippet for youBoth1 line
- Search-result title is leaving room on the tableBoth1 line
- No canonical tag, so duplicate URLs split the page's rankingBoth1 line
Effort is a rough read from the outside: "CSS only" means no new assets or backend work, "1 line" means a single tag, "Dev afternoon" means a developer needs to touch tracking or scripts.
06What this report cannot tell you
Everything above is from the outside, looking at the page on a simulated phone and desktop. The questions that actually decide revenue need real visitors. Install the Harvv pixel (one script tag, 16 KB, zero personal data, no engineering project) and within about 72 hours you'd know which buttons real customers tapped and missed, how often Google Analytics is missing visits, and exactly where mobile shoppers stalled and left. This report shows you where to look. The pixel shows you how often it happens, and to whom.
Drop the Harvv pixel on mcmaster.com and we turn this one-off scan into ongoing measured behavior: which taps miss, where sessions stall, and the real drop rates. Free to start, no card needed.
Add the pixel free07How we did this, and what it can't prove
- 4 mobile + 2 desktop loads of one URL from headless Chrome (iPhone viewport at 390px, desktop at 1366px), June 16, 2026. Enough loads to separate real defects from random noise, not a full-site crawl.
- Lab numbers, not real-user numbers (no field data was available for this run). Real devices on real networks run slower.
- Friction is inferred, not counted. We can prove a button is small. We can't, from the outside, count how often it causes a missed tap. That requires the pixel on a live page.
Prepared by Harvv. Last updated June 16, 2026.